
Preheat your oven to 375°F (190°C). Line a muffin pan with paper liners or grease the wells with cooking spray.
In a large mixing bowl, whisk together the eggs, buttermilk, sour cream, melted butter, canola oil, and vanilla extract until well combined.
Add the gluten-free flour blend, baking powder, baking soda, salt, and granulated sugar. Stir until just combined. Be careful not to overmix; a few lumps are okay.
If using mix-ins such as chocolate chips, raisins, or chopped nuts, gently fold them into the batter until evenly distributed.
Divide the batter evenly among the prepared muffin cups, filling each about 3/4 full.
Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Remove the muffins from the oven and allow them to cool in the muffin tin for 5 minutes before transferring them to a wire rack to cool completely.
Once cooled, store the gluten-free muffins in an airtight container at room temperature for up to 3 days, or freeze for longer storage.