• Preheat the oven to 400°F (200°C). Toss the quartered brussels sprouts with olive oil, salt, and pepper. Spread them in a single layer on a baking sheet and roast for 20-30 minutes, flipping halfway through, until golden brown.

Cook the Bacon:

• While the brussels sprouts roast, cook the bacon in a pan until crispy. Remove the bacon and drain all but one tablespoon of the bacon grease.

Sauté the Onions and Garlic:

• Add the butter to the pan with the bacon grease. Let it melt and bubble. Add the diced onion and sauté for 5-7 minutes until tender. Stir in the garlic and cook for about a minute, until fragrant.

Make the Sauce:

• Stir in the flour and cook for about a minute until it just begins to brown. Gradually whisk in the milk, followed by the mustard, miso (if using), and parmigiano Reggiano cheese. Let the mixture simmer for 3-5 minutes, until thickened.

Combine Everything:

• Add the roasted brussels sprouts and crispy bacon to the pan with the mustard cream sauce. Stir to combine, taste, and adjust seasoning with salt and pepper.

Serve:

• Serve warm, garnished with extra parmesan if desired, for a rich and flavorful side dish.