Preheat oven to 400 degrees.
Line a half size sheet pan with parchment paper.
Line bacon side-by-side on the sheet pan. Avoid overlapping if you can.
Measure brown sugar in a bowl and add the cayenne if you want it sweet and spicy. If you want to do a mix of both regular and spicy, the measurements are as follows: for every 4 pieces of bacon you need 1/4 brown sugar and 1/2 teaspoon of cayenne.
Spread half the brown sugar on top each piece of bacon and rub in.
Bake on the top rack for 20 minutes.
Remove the pan from the oven and flip the bacon. If the sugar is already burning on the pan, transfer bacon to a new parchment lined sheet pan. Be sure to flip each piece over.
Cover in the rest of the brown sugar, pressing down on each piece.
Put back in the oven on the top rack for 8-10 minutes.
Remove from the oven. Transfer each piece of bacon to a fresh piece of parchment paper. Allow to harden for 30 minutes.