In advance: Prepare floor, countertop and seats. Tint 12 oz. fondant black, 6 oz. gray. To make floor, cut two cake boards to 18 1/2 x 9 1/2 in., tape together and wrap with foil.
Roll out 12 oz. black and 12 oz. white fondant 1/8 in. thick and cut tiles using medium square Cut-Out. You will need approximately 30 black and 30 white tiles; cut 4 at a time and attach in alternating fashion to board which has been lightly brushed with Piping Gel.
Make countertop. Cut a cake board to 17 x 5 1/2 in.; wrap with foil. Lightly brush board with Piping Gel and cover with white fondant. Roll out gray fondant and cut 3/4 in. wide strips; attach to each countertop edge with Piping Gel.
To make seats: For posts, cut 4 lollipop sticks to 2 3/4 in. long, lightly brush with Piping Gel and cover with gray fondant. For base, cut gray fondant circle with large end of tip 1A . Make a hole in center of base with lollipop stick.
For cushions, roll out gray fondant and Red-Red/Christmas Red combination fondant slightly less than 1/4 in. thick; cut circles with large end of tip 127D. Stack red circle on gray; shape the rounded top with fingertips. Make a hole in bottom center of seat with lollipop stick. Let all seat pieces dry. Attach seat pieces with gray fondant thinned with water to piping consistency.
Ice 2-layer cake smooth; position on floor. Position countertop on cake top. Using Red-Red color, tint a small amount of fondant pink, roll out and cut napkins using medium square Cut-Out. Cut some squares in half for single-thick napkins and fold others in half for thicker napkins.
For spoons, cut a 1 x 3/8 in. piece of gray fondant for handle; roll and flatten a small ball for spoon end; attach with piping gel.
For extra sundaes, cut rounded end off spice drops, pipe tip 18 rosettes on wide end; position red jawbreakers for cherries. Cut out backdrop pattern and color areas with markers or colored pencils. Attach to cake board, cut to fit.
Trace easel back pattern and cut from cake board. Attach with glue to backdrop. Position napkins, spoons, candles and additional sundaes. Position stools and backdrop.
The rosette has the tight, swirling look of a rose, but is achieved in one continuous rotation, rather than with wrapped layers of petals. Single rosettes are also used as candleholders on top of a cupcake.