Cup peppers in half, leaving stems on, if desired. Remove seeds and ribs.
In a bowl, mix together cream cheese, cheddar cheese and taco seasoning with a fork. Fill each pepper half with this mixture, so it is level with the edges (not heaping). Place pepper half on a large rimmed sheet pan and continue until all peppers are stuffed.
In a small bowl, pour melted butter over panko crumbs and mix to combine. Top each stuffed pepper half with bread crumb mixture, lightly patting down to adhere. Return to sheet pan.
Bake peppers for 15 minutes, turn oven off and turn broiler on. Broil for 2-3 minutes or until breadcrumbs are browned. Watch carefully! Cool slightly before serving.
Nutrition information is based on one serving, or 2 to 3 stuffed pepper halves. The size of the peppers can vary quite a bit.
Make ahead tip: Peppers can be stuffed up to a day ahead of time, covered, and refrigerated. Bake as directed.
To make jalapeño poppers, substitute jalapeño peppers for the mini sweet peppers.