Preheat your oven to 375°F.

Sauté chopped onions and garlic in a skillet over medium heat until fragrant and translucent, around 5 minutes.

Add the Swiss chard to the skillet, stirring occasionally until it wilts, about 3-4 minutes.

Layer half of the sliced potatoes in a greased baking dish, followed by half of the Swiss chard mixture. Repeat with another layer of potatoes and chard.

Combine cream, cheese, salt, and pepper in a bowl, then pour this mixture evenly over the layers in the baking dish.

Cover the casserole with aluminum foil and bake for 30 minutes.

Uncover and bake for an additional 15-20 minutes until golden brown and bubbling on top.