Preheat oven to 400.
Roast the bacon on a sheet pan about 10 to 12 minutes until crisp.
Make the cheese sauce: Melt butter in a heavy gauge pot, stir in the flour over medium heat. Cook until pale brown.
Heat the heavy cream in a separate pot. Pour into the pot with the "roux" (flour and butter). Stir vigorously and reduce a bit, until it is slightly thickened. Add Nutmeg, cheeses, and salt and pepper. Whisk until all the cheese is melted and the sauce is relatively thick. Adjust the seasoning and fold in the sage.
Cut the bread into small pieces, Circles are nice. Or you can do triangles, diamonds, or squares. Mix and match if you like. Spray with pan spray and toast on a grill or in a pan.
Slice the turkey thin enough to make sandwiches.
Split the tomatoes in 1/2
Assemble the "canapes": toast, turkey, bacon, and tomato. Top with the cheese sauce and pop under a broiler to bubble the top. Or, you can use a torch. The broiler works better here, though, as it gets heat into all the ingredients. Garnish with fresh herbs if desired and serve hot.