1. In a bowl, mix flour, 1/4 cup granulated sugar, the brown sugar, almonds, lemon peel, 1/2 teaspoon cinnamon, and the salt. With a mixer fitted with a paddle attachment, at low speed, or with your fingers, beat or rub in butter until mixture forms coarse crumbs and begins to come together.
2. In large bowl, mix rhubarb, remaining 3/4 cup granulated sugar, and remaining 1/4 teaspoon cinnamon. Pour into an 8-inch square baking pan and spread level. Sprinkle evenly with flour mixture.
3. Bake in a 375° regular or convection oven until juices are bubbly and topping is golden brown, 45 to 50 minutes (40 to 45 minutes in convection oven).
To toast the almonds, spread them in a baking pan and bake in a 350° oven until golden under skins, 8 to 10 minutes.