Preheat your oven to 375°F (190°C) so it’s ready when the potatoes are mixed and in the dish.

Peel the potatoes and cut them into even 1–1½-inch cubes so they cook uniformly.

Rinse the cut potatoes under cool water to remove excess surface starch.

Pro tip: Cut the potatoes into similar-sized pieces — it keeps the cooking time consistent and prevents some pieces from turning mushy while others stay hard.

Place the potatoes in a large pot and cover with cold water by about 1 inch. Add a big pinch of salt.

Bring to a rolling boil over high heat, then lower to a gentle simmer.

Cook 15–20 minutes (depending on cube size) until a fork or knife slides into a piece with no resistance.

Test a couple of pieces so you don’t overcook.

Pro tip: Always start in cold water — it helps the potatoes cook evenly from edge to center instead of turning the outside to mush before the inside’s done.

Pour the potatoes into a colander and let them drain well.

Return the drained potatoes to the still-warm pot and place it back on the stove over the lowest heat for 1–2 minutes, shaking the pot occasionally to allow steam to escape.

This step removes excess moisture so the mash won’t be watery.

Pro tip: Drying the potatoes in the hot pot is a small extra step that makes a big difference — it keeps the finished texture light and not gluey.

While the potatoes are steaming off, warm the milk and heavy cream together with the butter in a small saucepan just until the butter melts (do not boil). Add the minced garlic to this mixture if you’re using it so it softens and mellows.

Use a potato ricer, masher, or hand mixer to break down the potatoes — do this while they’re hot for the silkiest result.

Slowly pour the warm milk/butter mixture into the potatoes while mashing, a little at a time, until you reach a creamy consistency you like.

Beat the eggs in a small bowl. Temper the eggs by whisking in 2–3 tablespoons of the hot potato mixture into the eggs, then stir the warmed eggs back into the main bowl (this prevents scrambling and helps the potatoes set nicely in the oven).

Fold in most of the shredded cheddar and Parmesan, reserving a handful to sprinkle on top.

Pro tip: Warm dairy keeps the potatoes fluffy — cold milk straight into hot potatoes can make the texture gluey.

Taste and season with salt and plenty of black pepper. Adjust butter, cheese, or milk for creaminess and flavor.

Scrape the mashed mixture into a buttered 9x13 baking dish (or similar), smoothing the top with a spatula. Dot with a few small pats of butter for extra flavor and browning.

Sprinkle the reserved cheddar and Parmesan evenly over the top.

Bake at 375°F (190°C) for 25–30 minutes until the center is hot and the top is bubbling and golden.

For a deeper, crispier top, switch to broil for 30–90 seconds at the end — WATCH closely so it doesn’t burn.

Pro tip: If you plan to broil, move the rack up one level before putting the dish in the oven and stand right there — that last-minute browning happens fast.

Remove from the oven and let rest for 5–10 minutes — this helps the potatoes set so they scoop nicely.

Sprinkle chopped fresh parsley over the top for color and freshness.

Serve straight from the dish while it’s warm and gooey.