A light, delicate, almond-scented sheet cake is topped with swirls of a smooth, creamy, almond frosting. Perfect for birthdays, picnics, or a family dessert, this cake is ideal for almond lovers. The flour frosting technique yields a silky icing that is easy to top with an extra garnish: berries, pears, figs, toasted nuts, or chocolate would all be excellent. —Posie (Harwood) Brien
Preheat your oven to 350°F. Grease and flour a 9" x 13" cake pan.
Whisk together the flour and baking powder; set aside.
In a large bowl, cream together the butter and sugar until light and fluffy. Add the eggs, one at a time, until each is well-incorporated. Add the almond extract and mix well.
Add the flour mixture and the milk in three additions, alternating between each. Mix until the batter comes together.
Mix in the almond flour.
Pour the batter into your prepared pan and smooth with a spatula to level the top. Bake for 20-25 minutes, or until a tester inserted in the middle comes out clean.
Let the cake cool completely in the pan before frosting.
For the frosting
Add the milk, flour, and salt to a medium saucepan and whisk until smooth.
Cook over medium heat, whisking constantly, until the mixture thickens and just begins to boil (about 5 minutes). Remove from heat and let cool for 10 minutes until the mixture is warm but not hot. (If the mixture is too warm, it'll melt the butter in the next step.)
With an electric mixer, beat the butter with the sugar and almond extract until very light and fluffy. Add the warm milk mixture, one spoonful at a time, until the frosting gets pillowy and smooth. Frost the cooled cake and serve!