1-First, preheat your oven to 400 degrees Fahrenheit and butter an oven-proof baking dish to prevent sticking and add extra flavor.

2-Next, in a large saucepan, bring salted water to a boil, then add the Brussel Sprouts. Cook them for 6 to 8 minutes until they turn bright green and slightly softened, then remove from heat and transfer to ice water to stop the cooking process and keep them crisp.

3-For the cream sauce, melt the butter over medium heat in a saucepan and stir in the flour, cooking for about 1 minute until smooth. Gradually whisk in the cream or milk and add the garlic, then cook for about 3 minutes while whisking occasionally until the sauce thickens. Season it with salt, pepper, and thyme if you’re using it.

4-Now, drain and halve the Brussel Sprouts, then layer half of them evenly in your prepared baking dish, followed by half of the grated cheese. Pour the cream sauce over the sprouts and cheese, and top with the remaining sprouts and cheese.

5-Finally, bake in the preheated oven for 12 to 15 minutes until it’s bubbly and golden on top. The total approximate active cooking and baking time is 25 to 30 minutes, not counting prep for trimming and halving the sprouts. If you’re making a vegan version, swap in plant-based alternatives at each stage to keep things tasty.