Bring salted water to a boil, cook conchiglie for 10-15 minutes and reserve some of the pasta water.
Get started on your sauce while the conchiglie is cooking. Melt butter in a saucepan on a low heat. Once the butter has melted add flour and stir well until well combined. Remove the saucepan from the heat, add milk gradually and stir well.
Return the saucepan to a medium/high heat and bring to a boil. When the sauce begins to bubble season the sauce with salt, pepper, garlic powder and onion powder. Then, lower the heat and cook for 10 minutes.
After 10 minutes turn off the heat, add cheese, peas and broccoli (add peas and broccoli at the previous step if you prefer them softer). Then, adjust the seasoning if necessary.
Finally, add conchiglie to the cheesy sauce, stir well and get ready to serve.