Melt the butter in the top part of a double boiler over simmering water.
In a bowl, beat the eggs with the sugar and add the gelatin. Add to the melted butter and cook, stirring constantly, until thickened, 6 to 8 minutes. Remove from the heat.
Add ½ cup of the crushed amaretti and the amaretto. Blend well. Cool, then refrigerate until the mixture jus