This savory buttermilk, herb, and onion tart is what I make when I want dinner to feel a little fancy on a Tuesday. Sweet onions melt into a tangy buttermilk-egg custard scented with basil, thyme, tarragon, and oregano, all nestled in a pre-baked whole wheat crust.
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 (1.23 oz) butter, divided
• 3 medium onions, diced
• 4 large eggs
• 1.5 cups / 360 ml buttermilk
• 2 cloves garlic, minced
• 0.5 tsp (2.5 ml) dried basil
• 0.25 tsp (1.3 ml) dried thyme
• 0.25 tsp (1.3 ml) dried tarragon, crumbled
• 0.25 tsp (1.3 ml) dried oregano
• 0.5 tsp (2.5 ml) 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 (23 ml / 0.8 fl oz) 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 (15 ml / 0.5 fl oz) 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 / 7.5 ml / 0.3 fl oz 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 / 360 ml unsweetened soy milk mixed with 1.5 tbsp / 23 ml 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 (0.63 oz / 17.9 g) 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 (240 ml) 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.
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Savory Buttermilk, Herb, and Onion Tart
Ingredients
Method
- Preheat your oven to 375°F / 190°C. Have your pre-baked pie crust ready on a wire rack.
- In a medium skillet over medium heat, melt 1. 5 tablespoons (75 ml / 2.5 fl oz) 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.
- 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.
- Sprinkle the grated cheese evenly over the bottom of the pre-baked pie crust. Carefully pour the buttermilk and egg mixture over the cheese.
- Cut the remaining 1 tablespoon (15 ml / 0.5 fl oz) of butter into small pieces and dot them over the top of the tart.
- Bake for 25 to 30 minutes, or until the center is just set and a knife inserted near the middle comes out clean.
- Let the tart cool on a wire rack for at least 20 minutes before slicing. This helps it set up properly.
- Serve warm.
