Preheat the oven to 180°C / 350°F.

Peel the 800 g Agria potatoes.

Slice the peeled potatoes into thin 3 mm / 1/8-inch rounds.

Thinly slice the 2 onions and finely slice the garlic clove.

Melt about 15 g of the butter in the frying pan over medium-low heat.

Sweat the sliced onions and garlic for 5 minutes without browning them.

Arrange one layer of sliced potatoes in the ovenproof baking dish.

Season the potato layer with a portion of the salt and black pepper.

Scatter a portion of the softened onions and garlic over the potatoes.

Dot the layer with small pieces of the remaining butter.

Repeat the potato, seasoning, onion, garlic, and butter layers until all ingredients are used.

Finish with a layer of potatoes and dot the top with the last pieces of butter.

Pour up to 500 ml hot broth into the dish until it just reaches the top potato layer without submerging it.

Cover the dish tightly with aluminum foil.

Bake the covered dish for 35 minutes at 180°C / 350°F.

Remove the aluminum foil and bake for 30 more minutes until tender and lightly golden.

Rest the pommes boulangères for 5 minutes before serving.