Grease a 9x13” glass baking dish.
Set aside.
Peel and slice sweet potatoes.
Set aside.
In a two-quart saucepan, melt butter over medium heat.
Add onion, garlic, bell pepper and leek and sauté about 5 minutes until veggies become almost tender.
Stir in gluten free flour and allow to cook an additional 30 seconds.
Slowly add whipping cream about 1/8 cup at a time until all of the cream is incorporated.
Add parsley, thyme, marjoram, salt and pepper.
Reduce heat to low and heat through until mixture thickens.
Layer half of the sweet potatoes into bottom of greased baking dish.
Sprinkle half of the ham over top.
Dollop or ladle half of the cream sauce over top of ham.
Repeat layers once.
Cover with foil.
Bake at 350° for about one-and-a-half hours, or until sweet potatoes are tender.
Remove from oven.
Stir ingredients with a wooden spoon to mix layers.
Garnish with sliced green onions, parsley and thyme, if desired.