Preheat the oven to 450 degrees F. Fill a large pot with 2 inches of water and a place a steaming basket over the top. Place the pot over high heat. Once boiling, add the clams to the basket and cover for 1-3 minutes, until just barely opened.
Open the clams and twist off the top shell. Lay the bottom with the clam on a baking sheet. Repeat with the rest.
Heat a large skillet over medium. Add the chopped bacon and cook until brown. Add the red pepper, shallot, garlic and rosemary.
Sauté another 3-5 minutes until the onions are soft, then add the panko breadcrumbs. Once the breadcrumbs are toasted, squeeze the lemon juice over the top and taste for salt and pepper.
Scoop the bacon mixture on top of the clams, distributing evenly.
Sprinkle a little Parmesan cheese over the tops. Bake for approximately 5-6 minutes—until the tops are crisp. Serve warm.