Step 1

Stir together sugar and lemon zest in small bowl until combined; set aside.

Step 2

Preheat oven to 425 degrees and set rack in center of oven. Spray inside of muffin tin with cooking spray.

Step 3

Bring 1 cup blueberries and 1 teaspoon sugar to simmer in small saucepan over medium heat. Cook, mashing berries with large spoon or potato masher until mixture is thickened and reduced to 1/3-1/4 cup, about 5 minutes. Transfer cooked blueberry mixture to small bowl and place in refrigerator while preparing muffin batter. This can also be made a day or two ahead of time.

Step 4

Place 1 1/4 cups sugar, and softened butter into the bowl of a stand mixer or large bowl. Mix until blended. Add eggs, oil, buttermilk and vanilla to bowl. Mix until blended on medium speed. Turn off mixer.

Step 5

Dump flour, baking powder, salt and baking soda into the bowl of wet ingredients. Turn mixer to low and mix just until the flour dissapears and there are no longer any white streaks in the batter. Do not over mix. Do not mix on high speed.

Step 6

Using a spatula or large spoon, fold (in about 3-4 turns) remaining 1 cup of blueberries into batter until incorporated.

Step 7

Use cookie scoop or large spoon to divide batter equally among prepared muffin cups (batter should completely fill cups and mound slightly).

Step 8

Spoon a teaspoon of cooked berry mixture on top of each mound of batter. Sprinkle lemon sugar over muffins. See photos on post.

Step 9

Bake until muffin tops are golden, 18 to 20 minutes, rotate muffin tin halfway through baking time if needed. Insert a toothpick into center of muffin to test for doneness.

Step 10

Cool muffins in tin for 5 minutes, then remove and set on wire rack and let cool at least 5 minutes before serving. Serve warm or at room temperature.