Cook the whole-grain penne in a large pot of salted boiling water according to package directions until al dente; drain and set aside.
Heat 1 tablespoon of the olive oil in a large skillet over medium-low heat.
Add the minced garlic and sauté about 1 minute, until fragrant but not browned.
Add the chopped sun-dried tomatoes, black pepper, salt to taste, and crushed red pepper flakes; cook, stirring, about 5 minutes until the tomatoes soften.
Stir in the cooked penne and the remaining 1 tablespoon olive oil; toss to coat, cover, and cook on low for 2 minutes.
Add the pine nuts and baby spinach and toss until the spinach begins to wilt.
Turn off the heat, cover and let the spinach slightly wilt for about 2 minutes.
Sprinkle the feta cheese over the pasta, toss gently to combine, and serve.