Preheat the oven to 375°F (190°C).
In a large skillet over medium-high heat, cook the bacon until crispy. Drain and set aside on a paper towel.
Bring a large pot of salted water to a boil. Add cauliflower and cook for 3 minutes. Drain well.
In the same pot, melt the butter. Whisk in the flour, stirring constantly until blended. Gradually add the milk, continuing to stir until the sauce thickens and becomes creamy.
Remove from heat, and stir in the cheese, nutmeg, salt, and pepper.
Add the cauliflower and bacon to the cheese sauce, tossing to combine. Transfer to a 9×13-inch baking dish. Top with breadcrumbs and additional cheese.
Bake for 30 minutes or until the top is golden and bubbly.
Garnish with fresh parsley before serving.
