Gluten-Free Yellow Cupcakes

Preparing to bake: Heat the oven to 375 degrees F. Grease two 12-cup muffin tins.
(For best results, use cupcake liners here.)
Combining the dry ingredients: Whisk together the flour mix, the psyllium, baking powder, baking soda, and salt.
Set aside.
Creaming the butter and sugar: Put the butter into the bowl of a stand mixer.
Using the paddle attachment at medium speed, whirl the butter and sugar together until they are thoroughly combined, creamy, and fluffy, about 3 minutes.
Be sure to scrape down the sides of the bowl with a rubber spatula once in a while.
Combining the wet ingredients: Whisk together the eggs, egg yolks, and vanilla extract.
Set aside.
Finishing the batter: With the stand mixer running, add the egg mixture, one tablespoon at a time, to the creamed butter and sugar.
When the entire mixture is incorporated into the butter and sugar mixture, add 1/3 of the dry ingredients to the bowl.
When there is no visible sign of flour, add 1/2 of the buttermilk.
When that is incorporated, repeat this process, ending with the dry ingredients.
Baking the cupcakes: Using a small ice cream scoop, spoon enough cake batter into the prepared muffin tins to fill each one 2/3 of the way.
Put the tin into the oven and bake until the cupcakes are slightly firm to the touch and a toothpick inserted into the cupcakes comes out clean, 20 to 30 minutes.
Allow the cupcakes to cool in the tins for 15 minutes.
Run a butter knife around the edges of the cupcakes, then turn them onto a cooling rack.