In a medium bowl, mix the flour, baking powder, baking soda, and salt. Set aside.
2 ¼ cups All-purpose flour, 2 teaspoon Baking powder, ½ teaspoon Baking soda, ½ teaspoon Salt
In a separate bowl, mix the sugar, melted butter (make sure it is cooled), eggs, sour cream, buttermilk, vanilla, and zest of 1 lemon.
1 cup White granulated sugar, ½ cup Unsalted butter, 2 Large eggs, ¼ cup Sour cream, 1 cup Buttermilk, 1 teaspoon Pure vanilla extract, Zest of 1 lemon
Pour the wet ingredients into the dry. Mix until just combined. Mix the raspberries with 1 Tablespoon of flour. Add in frozen raspberries and use a rubber spatula to mix in the berries.
1 cup Raspberries, 1 tablespoon All-purpose flour
Cover the bowl and let it rest for 1 hour.
Preheat the oven to 425°F. Line a 12 cup muffin pan with muffin liners. TIP: The best way to get extra domed muffin tops is to only add batter to every other muffin cup.
Use a large cookie scoop to scoop the batter into the muffin liners. It should be full to the top to get the biggest muffins. Top with coarse sugar.
Coarse sugar
Bake for 5 minutes at 425°F. Lower the oven temperature to 350°F. Bake for another 10-13 minutes until a toothpick inserted comes out clean.
Let the muffins sit in the hot pans for 10 minutes before transferring to a cooling rack.