Fill a large bowl with cold water. Add clams and cornmeal and let soak for about 30 minutes. The clams will draw the cornmeal in and clean everything out really nicely. Drain clams and rinse well to discard any sand and cornmeal.
In a large pot on medium high heat melt butter and olive oil. Add onions and saute for about 5 minutes or until they begin to brown. Using a garlic press mince the garlic into the pot, stir and cook for about 1 minute more.
Add wine and clams and reduce heat to medium. Cook clams for about 8 - 12 minutes or until all shells are open.
Meanwhile, make parmesan drizzle by melting butter and cream cheese in a saucepan. When melted whisk to combine. Add milk and half and half to flour and whisk until no lumps remain. Whisk mixture into butter and cream cheese in pan and add parmesan cheese. Continue to whisk until slightly thickened. Keep warm.
Pour clams and any liquid into a large serving bowl and top with diced tomatoes, parsley, and a sprinkle of red pepper flakes. Salt and pepper to taste if desired.
To serve, place pasta in a shallow bowl and top with some of the clams making sure to spoon some of the delicious sauce on top. Drizzle with the parmesan drizzle.