Blueberry Muffins Sourdough

Dry

1.5 cups gluten free flour
1 cup (200 g) granulated sugar
1 teaspoons baking powder
.5 teaspoon baking soda
.5 teaspoon salt
1 tablespoon corn starch
zest of half a lemon
1.5 cups (150 g) blueberries (fresh or frozen)

Wet Ingredients

10 tablespoons (113 g) butter (melted)
2 large eggs
.5 cup (125 g) sourdough starter discard
3 tablespoons coconut milk
1 teaspoon (5 g) vanilla extract

Crumb Topping
4 tablespoons (45 g) butter ( melted)
½ cup (100 g) granulated sugar
½ cup (60 g) all purpose flour

Mix dry, mix wet. combine and bake at 350 for 25 minutes in cast iron muffin tins