Line a baking sheet with parchment paper.
Combine the sugars, mustard, cayenne and pepper in a small bowl.
Spread the sugar mixture evenly on the parchment in the baking sheet & let it dry out overnight.
When you’re ready to bake, preheat oven to 225 degrees.
Line the bottom of a roasting pan with aluminum foil.
Finely grind the dried sugar mixture in a blender or food processor and pourinto a shallow bowl or plate.
Dredge each slice of bacon completely in the sugar mixture and lay it on the rack of the roasting pan. This will allow the drippings to fall onto the foil below, keeping the bacon crisp.
Bake for 45 to 65 minutes (without turning), until the bacon is brown,bubbly, and crisp.
Be sure to watch carefully so it doesn't burn.
Remove bacon slices with a spatula and serve warm or at room temperature.