Preheat the oven to 350 degrees.

In a medium skillet, melt the butter over medium-high heat. Add the mushrooms and saute until they begin to release their moisture, about 3 minutes. Add the shallots and continue to saute until the mushrooms are tender and deeply brown, about 3 more minutes. Pour in the wine and scrape up any browned bits that have formed on the bottom of the pan. Add the salt and sage and cook until the wine is fully absorbed. Remove from the heat.

Meanwhile, remove the brie from its box, discard the paper, and carefully saw off the top rind. Discard . Place the brie back in the box, and carefully fit a sheet of foil around the base (note: if you don’t have a box, simply create a little foil bundle for it). Place the brie on a baking sheet and spread the mushroom mixture on top of it.

Bake in the oven for 15 minutes, until the cheese is fully melted and oozing over the sides. Alternatively, you can chill in the fridge for up to 5 hours, until you’re ready to bake and serve!

Either serve directly in the box, or carefully remove it using kitchen shears and slide the brie onto a platter. Serve immediately alongside crackers or toasted baguette.