Preheat the oven to 325°. Generously butter a 9-by-2 1/2-inch springform pan. Press the almonds evenly over the base and sides of the pan.
In a large bowl, combine the butter, sugar, lemon zest, lemon juice and cinnamon and beat until light and fluffy, about 3 minutes. Beat in the eggs one at a time.
Sift together the cake flour and baking powder. Stir one-third of the milk into the batter, then add one-third of the flour. Repeat twice more, stirring just until the ingredients are incorporated and the batter is smooth; do not overmix.
Scrape the batter into the prepared pan and bake for about 1 hour and 25 minutes, or until the cake is well browned and a tester inserted in the center comes out clean. Let cool on a rack for 20 minutes before unmolding. Serve the cake upside down to show the almond crust.