Parmesan Bread Pudding with Broccoli Rabe and Pancetta

INGREDIENTS

• 1/2 teaspoon crushed red pepper flakes
• 6 large eggs
• 1/2 teaspoon freshly ground black pepper plus more
• 1/2 pound country-style white bread, cut into 1" pieces (about 8 cups)
• 2 teaspoons kosher salt plus more
• 1 1/2 cups whole milk
• 6 thin slices pancetta (Italian bacon)
• 1/2 cup plus 2 tablespoons finely grated Parmesan
• 2 garlic cloves, thinly sliced
• 1 tablespoon olive oil
• 1 medium bunch broccoli rabe (rapini), trimmed, cut into 1/2" pieces