Line a muffin tin with 12 liners and set aside.
In a small bowl whisk together the all-purpose flour, baking powder, salt and ground cardamom (if using). Set aside.
2 cups (250 g) all-purpose flour, spooned and leveled, 1 tablespoon baking powder, ½ teaspoon salt, 1 teaspoon ground cardamom (optional)
Add the blueberries to a small, separate bowl and sprinkle a 1 tablespoon of flour over them. Stir to coat, then set aside. (This helps the berries not sink to the bottom of the muffins while baking.
12 oz (340 g) fresh blueberries, 1 tablespoon (8 g) all-purpose flour
In a large bowl, whisk together the melted butter, granulated white sugar, eggs, sour cream, milk and vanilla extract.
½ cup (112 g) unsalted butter, melted, 1 cup (200 g) granulated white sugar, 2 eggs, at room temperature, 1 teaspoon vanilla extract, ½ cup (122 g) sour cream, ½ cup (120 ml) whole milk, at room temperature
Add the dry ingredients to the wet ingredients and whisk just until combined.
Add in the blueberries and gently fold them into the batter with a rubber spatula.
Cover the batter with plastic wrap and let it rest at room temperature for 1 hour. (This helps the muffins to be extra fluffy.)
Preheat the oven to 350 degrees.
After one hour scoop the batter into the prepared muffin pan. Be careful not to mix the batter around after it has rested, just scoop it into each liner. Add extra blueberries on top of each muffin and sprinkle with turbinado sugar.
3 oz (85 g) fresh blueberries, 2 tablespoon (24 g) turbinado sugar
Bake the muffins for 29-34 minutes. Let them cool for 10 minutes in the pan, then transfer them to a cooling rack to cool just until warm. Then enjoy!