For Cake

Preheat oven to 325 degrees.

Lightly grease a 9 x 5″ loaf pan. Line the bottom and short sides with parchment paper, allowing the ends to hang over for easy removal of the loaf after baking.

In a medium bowl, whisk together flours, baking powder, and salt. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugar on medium speed until light and fluffy. About 4 minutes.

Add the eggs and egg yolks, one at time until fully incorporated, scraping the sides of the bowl as needed.

Add the vanilla, mixing until well combined.

Beat the mixture until light and fluffy on medium speed until well combined.

Add the flour to the egg mixture, alternating with the milk and yogurt. Begin and end with the flour mixture.

Once combined, remove the bowl from the stand mixer and stir in the rainbow sprinkles using a spatula or wooden spoon.

Pour the batter into the prepared loaf pan using an offset spatula to gently smooth the top.

Bake for 60-65 minutes, checking the cake at 50 minutes. If the top is browning too quickly, cover the top loosely with aluminum foil.

Cake is done when it springs back when gently pressed on top and a toothpick inserted in the center of the loaf comes out clean.

Remove the cake from the oven and allow to cool for 10 minutes in the pan.

Using the parchment paper ends, pull the loaf from the pan and place on a cooling rack to cool completely.

For Glaze

Whisk the confectioner’s sugar, milk and yogurt together in a medium bowl until smooth. If the glaze is too stiff, add more milk. If too thin, add more confectioner’s sugar.

Pour over the top of the cooled cake, allowing the glaze to drip off the sides. Let the frosting sit for 10 to 15 minutes before slicing.