Cashew Mousse

Blend cashews, sugar, and 1 cup water in a blender until very smooth, about 2 minutes. Pour mixture into a fine-mesh sieve set over a large glass measure and let drain (gently stir if necessary but do not press on solids) until 1 1/2 cups cashew milk accumulates in cup (discard solids). Sprinkle gelatin over remaining tablespoon water (cold) in a 1- to 1 1/2-quart saucepan and let stand 1 minute to soften. Heat over low heat until gelatin is melted, then add cashew milk and liqueur and heat, stirring, until mixture is thickened (do not simmer), about 6 minutes. Cool to room temperature, stirring occasionally. Whisk cream until it just holds stiff peaks, then fold cream into cooled cashew- milk mixture gently but thoroughly and divide among serving bowls. Chill, covered, until set, at least 3 hours.