Preheat your oven to 350°F (175°C). Line a muffin tin with paper liners to prepare for your batter.
In a medium bowl, whisk together the gluten free 1-to-1 flour, baking soda, baking powder, and salt. Set aside.
In a large mixing bowl, using an electric mixer, cream together the room temperature unsalted butter and granulated sugar until light and fluffy, about 2-3 minutes.
Add the eggs, one at a time, mixing well after each addition. Then, add the vanilla extract and mix until combined.
In a separate bowl, combine the milk and plain Greek yogurt. Gradually add this mixture to the butter mixture, blending until smooth.
Slowly add the dry ingredient mixture to the wet ingredients, mixing until just combined. Be careful not to overmix.
Using a spatula, gently fold in the rainbow sprinkles until evenly distributed throughout the batter.
Scoop the batter into the prepared muffin tin, filling each liner about two-thirds full.
Bake in the preheated oven for 18-20 minutes or until a toothpick inserted into the center comes out clean.
Once baked, remove the cupcakes from the oven and let them cool in the tin for about 5 minutes. Then, transfer to a wire rack to cool completely before frosting.
