Heat oven broiler to high. Toss the cauliflower with 2 tablespoons of olive oil, salt, and pepper. Place on a baking sheet and bake for 8-10 minutes, turning once.

Heat 1/4 cup of olive oil in a medium skillet over medium heat. Cook capers for 5 minutes. Remove with a slotted spoon.

Add the breadcrumbs and chile flakes to the pan with the oil and cook for 3-4 minutes or until crisp. Transfer to the plate with the capers.

Wipe the skillet clean and melt butter over medium heat. Cook until the butter has browned. Stir in the dijon mustard, garlic, salt, and pepper. Pour sauce into a small bowl.

Meanwhile, cook the penne according to the package directions. Drain, reserving 1/2 cup of pasta water.

Add the pasta to the skillet along with half of the breadcrumb and capers mixture. Stir in the sauce and the reserved pasta water. Add cauliflower and toss to combine. Top with remaining breadcrumb mixture.