Place broccoli florets, carrots, onion, garlic, and vegetable broth into your pressure cooker.
Cook on high for 12 minutes and do quick release of pressure.
While pressure cooker is cooking, make your cheese sauce.
Melt butter in medium saucepan over medium high heat.
Add flour and stir to combine with butter, and cook for 1 minute.
SLOWLY add milk, whisking continuously so it incorporates with the flour/butter.
Stir in cheese and mustard powder until cheese is melted.
Pour cheese sauce into pressure cooker.
Season with salt and pepper, as needed.
Enjoy!