• At least 30 minutes before mixing, take the butter, eggs, milk and sour cream out of the refrigerator to come to room temperature. Separate the eggs. Measure out the rest of the ingredients.
• Position the oven rack to the center position. Preheat the oven to 350°F/175°C. Prepare your baking pan(s) with non-stick spray and parchment paper or with paper liners if making cupcakes.

To make the cake

• Sift together the cake flour, baking powder, and baking soda. Add the salt, whisk together, and set aside.
• In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with a hand mixer, combine the butter and sugar. Cream together on medium speed until very light and fluffy, about 5 minutes. Stop the mixer and scrape down the sides and bottom of the bowl halfway through mixing. The mixture should be very pale yellow after mixing.
• With the mixer running on medium/low speed add the vanilla and almond extracts. Next, slowly add in the egg whites while the mixer continues running. Scrape down the sides of the bowl periodically as you slowly incorporate the egg whites.
• Mix the milk and sour cream together. Alternate adding the dry ingredients into the bowl in three additions with the milk/sour cream mixture in two additions, starting and stopping with the dry ingredients. Mix on medium speed in between each addition until fully incorporated.
• Transfer the batter into the prepared pan(s). Bake at 350°F/175°C. A sheet cake will take about 35-45 minutes. Layer cakes will take 22-26 minutes, and cupcakes will take 18-25 minutes. Pull out of the oven when the cake is firm but springs back when gently pressed in on the center, or when a cake tester comes out clean.
• Cool the cakes in their pan completely on a cooling rack before turning out of the pan and frosting.
• Store the cake covered in foil or plastic wrap at room temperature for up to 3 days.