In a large pot over medium-high heat, melt the butter
Add chopped onions and sliced celery
Cook for about 3-5 minutes or until onions become translucent
Add the garlic, thyme, and flour
Mix to make a flour base
Pour in milk and vegetable stock and whisk with the flour
Add clams with juices and mix in
Add cut potatoes and bay leaves
Boil for about 15 minutes
Add half & half, salt, pepper, parsley, and heavy cream
Cook, stirring occasionally until thickened up