Houmus mac and cheese

Another mac and cheese-type dish. We use a box of the small shell pasta and this sauce (measurements are approximate since we just make it to taste in true Neinerschts fashion):

1/4 cup houmus
2 cups milk
1 tablespoon flour
1/4 cup cold water
1/3 cup sharp cheddar cheese
1/3 cup parmesan cheese
1 tablespoon lemon juice

Put cold water and flour in a sealed jar and shake until smooth. Warm milk on medium heat, stirring occasionally. Add 1/4 cup houmus. Continue to stir. when mixture is close to boiling, add water and flour combination; simmer for one minute. Stir in cheese and lemon juice and pour over pasta.

We usually add frozen baby peas too - at the very end so they don't get overcooked. any type of vegetable would work. I also like to add about 1/4 cup of pureed carrots (I'm lazy and buy the baby food version) - the sweetness of the carrots goes nicely with the houmus.