Melt butter in a medium skillet over medium. Add panko, and cook, stirring often, until golden brown and toasted, about 3 minutes. Transfer to a heatproof bowl, and stir in thyme and 1/4 teaspoon of the salt. Mix in parsley, garlic, and the Parmigiano-Reggiano and pecorino Romano cheeses. Set aside.
Lay steaks flat on plastic wrap. Salt and pepper steaks and pound to ¼” thick. Evenly distribute and lay slices of Prosciutto on each steak.
Top with panko breadcrumb mixture.
Roll the steaks, prosciutto, and breadcrumbs and secure with cooking string or toothpicks. (I prefer string)
Heat oil in a large skillet and add steaks, and sauté the rolls, turning occasionally, until browned on all sides.
Add browned steaks to crock pot and top with tomato sauce. Cook on high for 4 hours.