1Preheat oven to 375 degrees F (190 degrees C). Spray 15 muffin cups with cooking spray.
2Lightly spoon 2 cups flour into a dry measuring cup; level with a knife. Combine flour, sugar, baking powder, baking soda, and salt in a bowl using a whisk; make a well in the center.
3Stir yogurt, buttermilk, butter, eggs, poppy seeds, and vanilla extract together in a separate bowl; add to flour mixture, stirring just until batter is moist. Spoon batter into prepared muffin cups.
4Bake in the preheated oven until tops are golden brown, about 18 minutes. Remove muffins from cups immediately and place on a wire rack.
Footnotes
Cook's Note:
For extra taste, add 1 tablespoon lemon or orange rind.