Cut into cubes about the size of a quarter. Try to keep them all the same size.

Add potatoes to a large pot of cold water that has been salted. Don't crowd them. Bring water to a boil over high heat, then reduce heat to medium and cook at a rapid simmer until potatoes can be easily pierced with a paring knife, about 12 minutes for chopped potatoes. Do not overcook them to the point they are falling apart.

Meanwhile, heat 2/3 cup olive oil on medium heat in a small saucepan. Add the garlic, rosemary, lemon zest, crushed red pepper, and 1/4 tsp. salt and black pepper, occasionally stirring, for 2 minutes. Set aside but don't allow it to cool lower than room temperature.

Drain potatoes. Push the hot potatoes through a potato ricer back into the pot, or return the potatoes to the pot and mash with a potato masher. Strain the oil mixture into the potatoes and add 1 cup of warm vegetable stock. Sprinkle salt and pepper to taste. Transfer the potatoes to a bowl, drizzle with oil, and sprinkle with fresh chopped parsley and additional salt and cracked pepper if desired.