- **Preheat Oven**: Preheat your oven to 425°F (218°C). Line a muffin tin with liners or grease lightly. 
- **Mix Dry Ingredients**: In a medium bowl, whisk together the gluten-free flour, baking powder, baking soda, and salt. 
- **Cream Butter and Sugar**: In a large bowl, beat the softened butter and sugar until light and fluffy. 
- **Add Wet Ingredients**: Beat in the eggs one at a time, then mix in the vanilla extract, yogurt, and milk. 
- **Combine Wet and Dry Ingredients**: Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix. 
- **Fold in Blueberries**: Gently fold in the blueberries using a spatula. 
- **Fill Muffin Tin**: Divide the batter evenly among the muffin cups, filling them to the top. Sprinkle with coarse sugar if desired. 
- **Bake**: Bake at 425°F for 5 minutes, then reduce the temperature to 375°F (190°C) and bake for an additional 15-20 minutes, or until a toothpick inserted into the center comes out clean. 
- **Cool**: Let the muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.