Bring a large pot of water to a boil. Add the whole potatoes to the pot and cook for 20 minutes or until fork tender. Drain the potatoes.
Preheat oven to 400 degrees.
Grease a baking sheet with non-stick cooking spray. Place the potatoes on the baking sheet and gently smash with a fork, potato masher, or the bottom of a glass. (Don't press down hard enough to break the potatoes apart. You want them to still hold their shape, just smashed.)
Bake for 20 minutes.
Stir together the garlic and melted butter. Spoon the garlic butter over the top of each potato and then season them with salt and pepper.
Bake for another 5-7 minutes. Remove the potatoes from the oven and sprinkle with chopped parsley for garnish if desired. Serve warm.
Notes
To help save time, you can boil the potatoes ahead of time and then keep them in the fridge until you're ready to bake. Add the potatoes to a bowl and cover with a damp paper towel. Microwave for 1-2 minutes, in 30-second intervals, until warmed so that you can easily smash the potatoes for baking.