Preheat oven to 425° F.
Place cauliflower on baking sheet that has been lightly coated with spray. Season with salt and pepper if desired.
Bake for 24 to 28 minutes, or until golden brown. Set aside.
While cauliflower is cooking, bring almond milk to a boil in medium saucepan over medium-high heat, stirring frequently. Reduce heat to medium-low.
Add cheese, pumpkin, and mustard; cook, stirring frequently, for 3 to 4 minutes, or until well blended.
Add cauliflower; mix well.
Pour cauliflower minute into 8 x 8-inch casserole dish that has been lightly coated with spray.
Top with bread crumbs.
Bake for 18 to 20 minutes, or until hot and bubbly.