Lay one chicken breast flat, using a chef or large knife cut down the seam of the chicken breast making sure not to cut all the way through.
Place the butterflied chicken breast on a large piece of plastic wrap and cover the chicken. Using a meat mallet, pound out the chicken breast increasing the size.
Remove the plastic wrap, add some salt.
Place the pepperoni in a shingle-like pattern over the chicken breast. Add as much as you fit. Using toothpicks, close/secure the chicken closed.
In a large bowl add 2 eggs and whip them together, in a second bowl add equal parts Italian breadcrumbs and panko breadcrumbs
Dip the pepperoni chicken breast into the egg first then the breadcrumbs. Making sure to cover well
In a skillet, add butter and melt, then add olive oil. Once melted add the chicken. Make sure the heat isn't too high or you're going to burn the breadcrumbs and butter. Medium to medium-high heat
Bast the chicken with a spoon. Pouring the hot butter on top of the chicken as it cooks.
Into a 375 oven after the chicken as a nice golden brown color from the basting - cooks for 8 to 10 minutes in the oven