Grease and line the bottoms of 2 8 or 9-inch round cake pans with circles of parchment.
In a small bowl, whisk together the 3 ½ cups gluten free flour, 3 teaspoons baking powder, and ¼ teaspoon salt.
In a large bowl and using an electric mixer on medium speed, cream the 1 cup unsalted butter, scraping down the sides of the bowl as necessary, until the butter is lighter in color, about 45 seconds. Then add the 2 cups granulated sugar in a steady stream and mix on medium speed until the mixture is very light in color and texture, about 4 to 5 minutes.
Add the 4 eggs one at a time, beating well after each addition, then beat for an additional 2 minutes.
With the mixer on low, add the flour mixture in four doses, alternating with the 1 cup whole milk in three doses. Scrape down the sides of the bowl in between additions.
Pour the batter into the prepared cake pans. Preheat the oven to 350℉ and let the batter rest while it heats, up to 30 minutes. Place the cake in the oven and bake for 25 to 35 minutes, or until a toothpick inserted in the center comes out clean.
Remove from the oven and set on a rack to cool for 10 minutes then turn out onto rack to finish cooling completely.
Place the 2 cups heavy cream and sifted 1 cup powdered sugar in a large bowl and beat until soft peaks form.
To assemble the cake, cut each layer in half and place 1 cake round on a serving plate. Spread it with ¼ cup of whipped cream. Add ⅓ cup of the 2 cups strawberries, then top with another cake round. Repeat this process 2 more times, then use the remaining whipped cream to frost the top and sides of the cake. Top the cake with 1 cup blueberries.
Notes
Use room temperature ingredients. Let the butter, eggs, and milk sit on the counter for about 15 minutes before mixing them together to ensure a smoother batter and even baking.
Rest the batter. For a velvety smooth crumb, rest the batter while the oven heats or up to 20 minutes. This allows the gluten free flour to hydrate, eliminating any gritty texture.
Cool the cake layers completely before assembling. I like to let my cake layers rest in the fridge for at least 30 minutes before I put together the cake, or even overnight. This will prevent the whipped cream from melting when it hits a warm cake, and helps the cake layers to firm up a bit.
For a make-ahead option: Bake the cake a day or two in advance and store it, tightly wrapped, in the fridge. Assemble with the whipped cream and fruit on the day you plan to serve it.
Use cold heavy cream for whipping. Cold cream whips faster and holds its shape better. And make sure to sift the powdered sugar before adding it to remove any lumps!
How to layer: I like to cut each cake layer in half and make a tall, stacked cake. However, you can just do a 2-layer cake to keep things simpler. Use ½ cup of whipped cream in the middle of the cake, and use the rest to frost the cake.
This recipe also works with regular all-purpose flour. Use 3 cups of all-purpose flour if you don’t need it to be gluten-free.