Prep the jalapeños: Make a cut under the stem, and one above the tip of the pepper. Cut along the sides (lenghtwise) to create a window and remove it. Remove and discard the seeds, veins and membranes. Place the jalapeño back together, set aside and continue with the rest. 

Make the filling: In a large bowl mix the onion, bell pepper, garlic, the three cheeses, salt and pepper until well combined. Preheat the oven to 400 º F.

Assemble: line a sheet pan with aluminum foil and rack, set aside. Stuff each jalapeño with the filling. Close it and scrape off any filling oozing out. Wrap 1 1/2 slices of bacon around the jalapeño, from top to bottom. Secure each end of the bacon with a  toothpick. Place on the rack and continue making the rest.

Bake them in the center of the oven for about 30-35 minutes or until they are cooked through, the cheese has lightly browned and is gently bubbling. When ready, remove from the oven. Let them cool down for about 5 minutes. Remove and discard the toothpicks before serving. Enjoy!