In a large stockpot fitted with a steamer basket, steam the veggies, covered, for 15-20 minutes until fork tender. You can also boil the veggies if you want to.
Transfer the veggies to a blender and add in 1 cup of half and half. Blend for 2-3 minutes until smooth, creamy and fully pureed. Strain the veggies if you want to, and set it aside.
In a large saucepan, cook the elbow noodles as directed on the package until al dente and drain well.
Melt the butter in a large saucepan and add in the flour, cooking and whisking for 2-3 minutes until golden brown. Now add the remaining 1⁄2 cup of half and half, stir and continue cooking until it begins to simmer, for about 2-4 minutes.
Now add in the strained veggie puree and salt and bring to it a low boil. Next, add in the cheese, one handful at a time, stirring well until the cheese is all added and melted.
Cook the sauce for 1-2 more minutes or until thickened and then carefully pour the cheese sauce over the cooked noodles in a large pot and fold together. Serve hot.
Notes
Want the mac and cheese to have a spicy kick? Add some cayenne or crushed red pepper flakes into the mix, or just add a splash of your favorite hot sauce.
You can also make the sauce in a huge batch and freeze it for later if you want to. Use a freezer safe container or bag and the sauce should stay good for up to 6 months.
This veggie packed cheese sauce can double up as a dip for your nachos or even as a sauce for your tacos.
If the sauce hasn't thickened up enough, you can let it simmer over low heat to let the liquid evaporate, or just add a simple cornstarch and water slurry into it to get it to thicken.
Experiment with other veggies like peas, spinach, kale, cherry tomatoes and edamame.
For a bit of texture, you can also top the pot of veggie mac and cheese with some toasted panko breadcrumbs.