In a large pot or deep skillet, melt the butter over medium heat. Add the minced garlic and red pepper flakes, sautéing for about 1 minute until fragrant, being careful not to burn the garlic.
Pour in the white wine and bring to a simmer. Allow it to cook for about 2-3 minutes to reduce slightly.
Add the cleaned mussels to the pot, cover with a lid, and cook for 5-7 minutes, or until the mussels have opened. Discard any mussels that remain closed.
Squeeze the lemon juice over the mussels and sprinkle with lemon zest, salt, and pepper. Stir gently to combine.
Remove from heat and garnish with chopped parsley before serving.