Cream together butter and cream cheese; add powdered sugar. Add vanilla and egg; mix well. Mix together salt, baking powder, flour and ground almonds; add gradually to butter mixture. Divide in half and add red food colouring to one half and green food colouring to the other half. Chill for two hours.
Roll each half of dough between wax paper into a 9 x 12-inch rectangle. Remove one sheet wax paper from each rectangle. Lay one layer of dough on top of the other and press together. Remove wax paper from the top of dough. Roll up dough tightly beginning with a long side, removing the wax paper on the bottom as you roll. Chill for at least 4 hours.
Heat oven to 400° F. Cut the roll of dough into 1/8- inch thick slices; place on ungreased baking sheet. Bake 8 to 10 minutes.