For the muffins
3 eggs (150 g, weighed out of shell) at room temperature, beaten
3/4 cup (6 fluid ounces) buttermilk, at room temperature
8 tablespoons (112 g) unsalted butter, melted and cooled
1 teaspoon pure vanilla extract
2 cups (280 g) all purpose gluten free flour
1 teaspoon xanthan gum (omit if your blend already contains it)
1 teaspoon baking powder
1/2 teaspoon baking soda
1/2 teaspoon kosher salt
1/2 cup (100 g) granulated sugar
1/4 cup (55 g) packed light brown sugar
Up to 1 cup of mix-in pieces (chocolate chips, raisins, chopped nuts) or crumble topping (see below)
For the (optional) crumble
4 tablespoons (56 g) unsalted butter, melted
1/2 cup (109 g) packed light brown sugar
1/2 cup (70 g) all purpose gluten free flour
1/4 teaspoon xanthan gum (omit if your blend already contains it)
1/8 teaspoon kosher salt
Preheat your oven to 350°F. Grease or line the wells of a standard 12-cup muffin tin and set it aside.
If you’d like to add the crumble to the tops of your muffins, make the crumble now. Place all of the (optional) crumble ingredients in a small bowl and mix to combine fully. Place in the refrigerator to chill while you make the muffins.
To make the muffins, in a medium-size bowl, place the eggs, buttermilk, butter and vanilla, and mix until well-combined. In a large bowl, place the flour, xanthan gum, baking powder, baking soda, salt, granulated sugar and brown sugar. Whisk to combine and break up any lumps in the brown sugar. Create a well in the center of the dry ingredients and add the egg and buttermilk mixture. Stir the wet ingredients into the dry ingredients until just combined. Don’t overmix. If adding any simple mix-ins like chocolate chips, add them to the batter now and mix just until evenly distributed throughout the batter.
Divide the batter evenly among the prepared wells of the muffin tin, smooth the tops with wet fingers. If you’re adding the crumble, remove the bowl from the refrigerator and break up the crumble into irregular pieces (none too large) with the tines of a fork. Sprinkle the crumble generously on the top of the muffin batter in the wells, and press to adhere the mixture to the muffin batter.
Place the pan in the center of the preheated oven and bake until the top of the center muffin springs back when pressed gently in the center, about 20 minutes. If you’ve added the crumble, those muffin may take another minute or so to bake fully. Remove from the oven and allow the muffins to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.