Start by washing the radishes and trimming off both ends. Cut each one in half or into thirds for even cooking.
Place your radishes in a pot and cover them with water. Bring everything to a boil and then reduce the heat, simmering until the radishes are tender, for about 15-20 minutes after the water hits a boil. While the radishes boil, grate your garlic on a microplane for even texture.
Once the radishes are fork-tender, drain the water and return them to the pot. Let them sit for a minute to allow any excess moisture to evaporate.
Then add the butter or oil to the pot with the radishes and begin mashing with a potato masher or fork. For a smoother texture, you can use a food processor or hand blender. If they're not able to be mashed with a hand blender, they didn't cook for long enough.
Stir in the heavy cream and minced garlic, continuing to mash until you reach your desired consistency. If you prefer a thinner mash, you can add some more cream or half & half little by little.
Season the mash with salt to taste, mixing well to ensure the salt is evenly distributed.Transfer the radish mash to a serving bowl; if desired, garnish with fresh chopped herbs like chives, parsley, or dill for an extra pop of flavor and color.