Cheesy Leek and Lentil Rolled Omelet with Artichokes

Nonstick cooking spray

medium leek, washed

unsalted butter, melted, divided

artichoke hearts, drained well and chopped

cooked green lentils

all-purpose flour

whole milk

heavy cream

large eggs

whole-grain mustard

scant teaspoon soy sauce or tamari

scant teaspoon freshly cracked black pepper

grated Monterey Jack cheese

chopped parsley