Cut the pancetta into 1/2-inch cubes and cook it in a skillet over medium-low heat for 10 to 15 minutes, until browned and crisp. (Pancetta is Italian bacon. You can find it in your Italian grocery or a specialty food store. Ask that it's cut 1/2-inch thick.).
Remove to paper towels and drain.
Place the tomatoes on a baking sheet and coat with olive oil.
Sprinkle with salt and pepper.
Roast for 15 to 20 minutes, until soft.
Wash the lettuce leaves carefully and spin-dry in a salad spinner.
Stack the leaves on a cutting board and cut them crosswise into 1 1/2-inch slices.
Place them in a large mixing bowl.
For the dressing, place the egg yolk (*if you're nervous about raw egg yolks, substitue 2 tablespoons of real mayonnaise), mustard, garlic, anchovies, lemon juice, salt, and pepper into the bowl of a food processor fitted with a steel blade.
Process until smooth.
With the food processor running, slowly pour the olive oil through the feed tube (as though you were making mayonnaise), until thick.
Add the 1/2 cup grated Parmesan cheese and pulse 3 times.
Toss the lettuce with enough dressing to moisten well.
Add 1 cup grated Parmesan and toss.
Divide the lettuce among 6 or 8 plates and sprinkle with the pancetta roasted tomatoes. Serve at room temperature.