Spread 1 tablespoon of softened butter over the bottom and sides of a 9-inch springform pan, dust with the 1 tablespoon all-purpose flour, and tap out the excess.
Line the bottom with a round of parchment paper.
Melt the remaining 12 tablespoons butter in the microwave and mix it with the granulated sugar together in a large bowl with a rubber spatula until combined.
Stir in the eggs, amaretto, almond extract, and lemon zest until smooth.
Sift the 1¼ cups all-purpose flour, almond flour, and salt into the bowl. Fold until just incorporated. The batter will be thick.
Scrape the batter into the prepared pan and smooth the top.
Sprinkle with the brown sugar, then scatter the sliced almonds evenly over the surface.
Bake for 35 to 40 minutes, until the top is deep golden and a toothpick inserted in the center comes out clean. If the edges darken before the center sets, tent it loosely with foil for the last 10 minutes.
Cool in the pan on a wire rack for 20 minutes. Run a knife around the edge, release the springform, and cool completely, about 40 minutes more.
Whip the heavy cream, crème fraîche, 1 tablespoon powdered sugar, and vanilla extract in a chilled bowl to soft peaks, about 2 minutes.
Dust the torte with the remaining tablespoon of powdered sugar, slice, and serve with the whipped crème fraîche.