Chop 8 ounces (⅔’s) pepperoni and transfer to a mixing bowl. Add 1/4 cup Parmesan, mozzarella, marinara, and oregano to pepperoni and mix together until completely combined.
To assemble: Stack two egg roll wrappers together and brush with beaten egg. Scoop ⅓ cup of filling onto the stacked wrappers and form into a log. Top ‘filling log’ with a few slices of remaining pepperoni. Fold in sides of wrappers, then tightly roll until sealed.
Repeat step 2 until all egg rolls have been rolled up.
Brush each egg roll with melted butter and roll in remaining Parmesan. Shake off any excess Parmesan transfer egg rolls to a parchment lined baking sheet, 1 inch apart.
Place egg rolls in freezer for at least 30 minutes (and up to 3 months).
Preheat oven to 375˚F.
Remove egg rolls from freezer and bake egg rolls for 25 to 30 minutes or until golden brown.
Remove egg rolls from oven and cool for 7 to 10 minutes. Serve with a side of marinara sauce for dipping.