Bring a large pot of salted water to a rolling boil. Add the gnocchi and cook according to package directions until they float to the surface, typically 2-3 minutes. Use a slotted spoon to remove them and set aside to drain. Don't rinse them as the starch helps them crisp up better.

Heat the olive oil in a large frying pan over medium-high heat. Once the oil shimmers, add the cooked gnocchi in a single layer. Let them sit undisturbed for 2-3 minutes to develop a golden crust.

Gently flip the gnocchi and cook another 2-3 minutes until crispy on multiple sides. You'll know they're ready when they have a deep golden color and sound slightly crispy when you stir them.

Lower the heat to medium and push the gnocchi to one side of the pan. Add the minced garlic to the cleared space and cook for about 1 minute until fragrant but not burned.

Add the fresh spinach to the pan and stir everything together. The spinach will wilt dramatically in about 2-3 minutes, reducing from 4 cups to roughly 1 cup. Season with salt, black pepper, and red pepper flakes if using.

Remove from heat and fold in the crumbled feta cheese. The residual heat will slightly soften the cheese while keeping its tangy bite. Serve immediately while the gnocchi are still crispy.