Preheat oven to 400 degrees. Lightly spray a 9-inch square baking dish with cooking spray.
Add tomatoes to baking dish and place block of feta in the middle of the tomatoes.
Sprinkle the garlic, Italian seasoning, red pepper flakes, and pepper over the tomatoes and feta.Drizzle the olive oil over everything.
Bake for 30 to 35 minutes.While it bakes, bring a pot of salted water to a boil and cook pasta according to package directions. Reserve 1/4 cup of pasta water. Drain.
Place sun-dried tomatoes and shrimp on top of tomatoes and feta and return to oven for 6 to 8 minutes or until shrimp are pink.
Add penne, spinach, and lemon juice to baking dish and stir until evenly mixed. Mix in enough reserved pasta liquid to thin the feta sauce a little.