Preheat the oven to 350 degrees Fahrenheit (175 degrees Celsius). Line two standard cupcake pans (or three minis) with cupcake liners. Set aside.

In the bowl of a stand mixer, beat the butter and sugars until light and fluffy, about 3 minutes. Add the vanilla bean paste and almond extract. With the mixing speed on low, add the egg, then the egg yolk, mixing until just combined.

In a medium-sized mixing bowl, whisk together the flour, cake flour, baking powder, baking soda, and salt. In a glass measuring cup, mix together the sour cream and milk. With the mixing speed on low, alternate adding the dry and wet ingredients. Mix until the batter is smooth and homogeneous (being careful not to overmix).

Remove the bowl from the stand and gently fold in the sprinkles. Scoop the batter into the cupcake liners, filling each ⅔ of the way full. Place in the oven and bake for 18–22 minutes (8–12 for minis), or until the cupcakes spring back when touched and are slightly golden brown on top.

Remove from the oven and allow to cool in the pans for 5 minutes before transferring to a wire rack to cool completely (about 25 minutes).

While the cupcakes are cooling, in the bowl of a stand mixer fitted with the whisk attachment, combine the butter, salt, vanilla, and almond. Beat until fluffy (2–3 minutes). With the mixing speed on low, add the heavy cream, then gradually add ½ cup of powdered sugar at a time until the mixture becomes soft but firm enough to hold its shape. Beat the frosting for an additional 3 minutes until light and fluffy. Transfer to a piping bag and pipe onto the cooled cupcakes as desired. Decorate with sprinkles.