Preheat the oven to 400F. Line a baking pan with parchment paper.
Combine 2 cups of cake flour, sugar, baking powder, and salt in a large bowl. Add half of the butter and whiz with the blade attachment of a food processor or rub it in with your fingertips until the mixture looks coarse but still with some larger chunks of butter. Add the remaining butter and pulse a few more times, until it resembles coarse meal. Beat the egg and milk in a small bowl and pour over the dry ingredients, whizzing a few times or tossing with a fork until just moistened. Gather the dough into ball on a lightly floured surface. Shape it into an 8 inch round about 3/4 inch thick. Using a sharp knife, cut the round into 8 equal wedges. Transfer to the parchment lined pan, leaving 2 inches of space between the wedges. Brush the tops and sides with milk.
Bake the scones until their tops are golden and a toothpick inserted into the centers comes out clean, about 14-15 minutes. Let cool for at least 10 minutes, and prepare the glaze.
Stir together the powdered sugar, milk, and almond extract in a small bowl until completely smooth. Drizzle over the warm scones and immediately sprinkle with toasted sliced almonds.
Serve warm or at room temperature. These are best eaten the day that they are made.