Position a rack in the middle of the oven and preheat to 350 degrees . Grease and flour a 10-inch (10-cup) bundt pan. Using a food processor, finely grind 1 the almonds and 1/4 cup brown sugar. Into a large bowl, sift the flour, salt and baking soda; whisk in the ground almond mixture. In a small bowl, whisk together the sour cream and vanilla.
Using a standing mixer, beat the butter on medium speed until creamy, about 2 minutes. Increase the speed to medium-high, add the remaining 1 3/4 cups brown sugar and beat, scraping the bowl occasionally, until light and fluffy, about 5 minutes. Add the eggs 1 at a time, beating well after each addition. At low speed, add the flour mixture in 3 batches, alternating with the sour cream mixture in 2 batches, beginning and ending with the flour mixture. Beat until just combined.
Transfer the batter to the prepared pan; smooth the top. Bake until a toothpick inserted in the center comes out clean, about 1 hour 10 minutes. Let the cake cool in the pan on a rack for 10 minutes. Invert the cake onto the rack, remove the pan and let the cake cool completely. [Make ahead: Wrap the cake in foil and store at room temperature overnight.]
Before serving, transfer the cake to a platter and dust lightly with confectioners sugar.