In a large stockpot or dutch oven fitted with a steamer basket, place enough water in the bottom just to reach the bottom of the basket and then add the carrots, cauliflower and zucchini into the basket.
Steam the veggies, covered, for 15-20 minutes until fork tender.
Carefully transfer the veggies to a blender and add in 1 cup of the half and half.
Blend for 2-3 minutes until smooth, creamy and fully pureed.
Strain the veggies through a fine mesh strainer and then set to the side.
In a large saucepan, cook the elbow noodles as directed on the package until al dente and then drain well.
While the noodles are cooking, melt the butter in a large saucepan and then whisk in the flour, cooking and whisking frequently for 2-3 minutes until golden brown and thick.
Gradually whisk in the remaining ½ cup of half and half, stirring and heating until it begins to simmer, about 2-4 minutes.
Once simmering, stir in the strained veggie puree and salt and bring to a low boil.
Add in the shredded cheddar cheese and sharp cheddar 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 or serving bowl and carefully fold together.
Serve hot.