Savory Buttermilk and Onion Tart Recipe

Side Dishes

March 22, 2026

Who knew that humble carton of buttermilk held the secret to the creamiest, most flavorful savory tart? This recipe is a game-changer! We’re swapping out heavy cream for tangy, light buttermilk, which creates a luscious, silky custard without weighing you down. Paired with sweet, tender sautéed onions and a blanket of melty Monterey Jack cheese, all nestled in a rustic whole wheat crust, this tart is pure comfort. It’s the perfect elegant-yet-easy dish for a weekend brunch, a light lunch with a side salad, or a fantastic way to finally use up that leftover buttermilk!

Ingredients

• 1 9-inch / 23 cm pre-baked whole wheat pie crust
• 2.5 tbsp / 35g butter, divided
• 3 medium onions, diced
• 4 large eggs
• 1.5 cups / 360 ml buttermilk
• 2 cloves garlic, minced
• 0.5 tsp dried basil
• 0.25 tsp dried thyme
• 0.25 tsp dried tarragon, crumbled
• 0.25 tsp dried oregano
• 0.5 tsp salt
• Freshly ground black pepper, to taste
• 1.5 cups / 6 oz / 170g grated Monterey Jack or Muenster cheese

Instructions

1. Preheat your oven to 375°F / 190°C. Have your pre-baked pie crust ready on a wire rack.
2. In a medium skillet over medium heat, melt 1.5 tablespoons of the butter. Add the diced onions and sauté for about 10 minutes, until they are tender and fragrant but not browned. Remove from the heat.
3. In a large bowl, whisk the eggs until they are well blended. Whisk in the buttermilk, minced garlic, basil, thyme, tarragon, oregano, salt, and a few grinds of black pepper. Stir in the cooked onions.
4. Sprinkle the grated cheese evenly over the bottom of the pre-baked pie crust. Carefully pour the buttermilk and egg mixture over the cheese.
5. Cut the remaining 1 tablespoon of butter into small pieces and dot them over the top of the tart.
6. Bake for 25 to 30 minutes, or until the center is just set and a knife inserted near the middle comes out clean.
7. Let the tart cool on a wire rack for at least 20 minutes before slicing. This helps it set up properly. Serve warm.

Nutritional Information

• Serving Size: 1 slice (serves 4)
• Calories: 380 kcal
• Protein: 18g
• Fat: 25g
• Carbohydrates: 22g
• (Note: This is an estimate and can vary based on the specific crust and cheese used.)

Pro Tips

• For a deeper, sweeter flavor, caramelize the onions slowly over low heat for 20-30 minutes instead of just sautéing.
• Feel free to swap the cheese! Gruyère, sharp white cheddar, or a sprinkle of Parmesan would also be delicious.
• The tart is done when the center is just set; it should still have a slight jiggle. It will continue to cook and firm up as it rests.
• If you have fresh herbs, use them! A good rule of thumb is to use three times the amount of fresh herbs as dried (e.g., 1.5 teaspoons of fresh basil).

FAQ

Q: Can I make this savory buttermilk tart vegan
A: Making this tart fully vegan requires several key substitutions. Use a plant-based butter, a certified vegan pie crust, and your favorite brand of vegan shredded cheese. For the custard, replace the buttermilk with a plant-based version (1.5 cups unsweetened soy milk mixed with 1.5 tbsp lemon juice) and use a liquid vegan egg substitute according to package directions. The final texture will differ from the original but will still be delicious.

Q: Is this vegetarian tart a good source of protein
A: Yes, with approximately 18 grams of protein per slice, this tart is a fantastic vegetarian protein source. The protein comes primarily from the eggs, buttermilk, and cheese, making it a satisfying and filling option for a main course at brunch or lunch.

Q: What other vegetables can I add to this tart
A: This recipe is very adaptable. For more veggie goodness, consider adding 1 cup of sautéed mushrooms, a cup of wilted spinach (squeezed very dry to remove all water), chopped roasted red peppers, or blanched asparagus tips. Simply add them to the crust along with the cheese before pouring in the custard.

Q: How should I store leftover buttermilk tart
A: To store leftovers, first let the tart cool completely to room temperature. Then, cover it tightly with plastic wrap or transfer slices to an airtight container. It will keep well in the refrigerator for up to 4 days. You can enjoy it cold or reheat gently in a 350°F / 175°C oven until warmed through.

0 0 votes
Article Rating
Subscribe
Notify of
guest

0 Comments
Oldest
Newest Most Voted
Inline Feedbacks
View all comments

More Vegetarian Recipes

Smiling woman in a brown top holds a bowl of creamy porridge with a wooden spoon in a sunlit kitchen.

Homemade Yogurt DAHI

Ingredients 1 qt (32 fl oz / 946 ml) fresh whole cow’s milk 3 tbsp (1.5 oz / 45 g) plain yogurt starter (homemade or commercial), smooth Optional for firmer body: 0.5 cup (2.3 oz / 65 g) non-instant, non-fat dry milk powder 0.33 cup (2.6 fl oz / 80 ml) milk, room...

A smiling woman in a rustic kitchen holds a clear glass jar filled with golden, homemade Black Pepper Ghee, which shows whole peppercorns suspended within it.

Black Pepper Ghee KALA MIRCH GHEE

Ingredients 3.0 lbs (48.0 oz / 1360g) high-quality unsalted butter (equivalent to roughly 6.0 cups before clarifying) 2.0 tbsp (1.0 oz / 28g) whole black, white, or dark green peppercorns 0.1 sq yards of food-grade cheesecloth (for wrapping) Instructions Cut the 3.0...

A smiling female chef wearing a blue apron stands in a bright kitchen, proudly holding a large glass jar of freshly made, homemade Jeera Ghee (cumin-flavored ghee) infused with curry leaves.

Cumin-Flavored Ghee JEERA GHEE

Ingredients Unsalted Butter: 3 lbs (48 oz / 1360g) Cumin Seeds: 3 tbsp (0.5 oz / 15g) Curry Leaves: 6 to 8 fresh or dried leaves (approx. 0.1 oz / 2g) Equipment: Cheesecloth and kitchen twine (for the bouquet garni) (Note: This recipe yields approximately 5 cups (40...

Smiling woman in a brown top holds a bowl of creamy porridge with a wooden spoon in a sunlit kitchen.

Homemade Yogurt DAHI

Ingredients 1 qt (32 fl oz / 946 ml) fresh whole cow’s milk 3 tbsp (1.5 oz / 45 g) plain yogurt starter (homemade or commercial), smooth Optional for firmer body: 0.5 cup (2.3 oz / 65 g) non-instant, non-fat dry milk powder 0.33 cup (2.6 fl oz / 80 ml) milk, room...

A smiling woman in a rustic kitchen holds a clear glass jar filled with golden, homemade Black Pepper Ghee, which shows whole peppercorns suspended within it.

Black Pepper Ghee KALA MIRCH GHEE

Ingredients 3.0 lbs (48.0 oz / 1360g) high-quality unsalted butter (equivalent to roughly 6.0 cups before clarifying) 2.0 tbsp (1.0 oz / 28g) whole black, white, or dark green peppercorns 0.1 sq yards of food-grade cheesecloth (for wrapping) Instructions Cut the 3.0...

A smiling female chef wearing a blue apron stands in a bright kitchen, proudly holding a large glass jar of freshly made, homemade Jeera Ghee (cumin-flavored ghee) infused with curry leaves.

Cumin-Flavored Ghee JEERA GHEE

Ingredients Unsalted Butter: 3 lbs (48 oz / 1360g) Cumin Seeds: 3 tbsp (0.5 oz / 15g) Curry Leaves: 6 to 8 fresh or dried leaves (approx. 0.1 oz / 2g) Equipment: Cheesecloth and kitchen twine (for the bouquet garni) (Note: This recipe yields approximately 5 cups (40...

A smiling woman in an apron holds a large glass jar of liquid Oven-Method Ghee with a wooden spoon in it, in a rustic kitchen setting with cooking supplies.

Oven-Method Ghee CHOOLA GHEE

Ingredients 16 oz (455 g) or 2.0 cups (32 tbsp) of unsalted butter A heavy-bottomed, thick-walled ovenproof pan Fine-mesh wire skimmer or metal spoon Cheesecloth or linen towel Glass storage containers Step-by-Step Instructions Preheat the oven to 300°F (150°C). Take...