Place the quartered red potatoes in a large pot and cover with cold water. Add a generous pinch of salt, then bring to a boil over medium-high heat. Cook until the potatoes are fork-tender but not falling apart — about 15-20 minutes. Drain thoroughly in a colander.
While the potatoes boil, melt the unsalted butter in a small saucepan over low heat. Stir in the olive oil, minced garlic, chopped rosemary, thyme, and half of the parsley. Let the mixture simmer gently for 2-3 minutes to infuse the butter with herb and garlic flavor. Remove from heat and set aside.
Preheat your oven to 425°F (220°C). Lightly oil a baking sheet. Arrange the drained potatoes on the sheet, spacing them evenly. Using a potato masher or the bottom of a sturdy glass, gently press down on each potato quarter until it’s about half an inch thick and flattened but still in one piece.
Drizzle the garlic herb butter generously over the smashed potatoes, making sure to coat all the nooks and crannies. Sprinkle with salt and freshly ground black pepper to taste. Roast in the preheated oven for 25-30 minutes, or until the edges are crispy and golden brown.
Once out of the oven, sprinkle the remaining fresh parsley over the potatoes for a pop of color and fresh flavor. Serve these Buttery Herb Smashed Red Potatoes hot alongside your favorite main dishes.