In the bowl of a stand mixer, add the cream cheese, sugar, vanilla, & cinnamon. Whip together until smooth and completely incorporated.
Spread 1/4 of the mixture evenly out over one side of a tortilla. Layer apples over one 1/2 of the tortilla. Fold over to close.
Melt 1 tbsp of butter in a flat bottomed skillet over medium low heat. When melted, transfer the quesadilla to the pan. Cook 1-2 minutes, or until golden brown.
Using two spatulas, flip the quesadilla, cooking another 1-2 minutes, until that side's also golden brown. Repeat for the remaining 3 quesadillas.
Using a basting brush, lightly brush one side of a cooked, crisp quesadilla with melted butter, sprinkle liberally with cinnamon sugar. Flip the quesadilla, repeat, and do for all of the remaining quesadillas.
Using a pizza cutter, cut the warm quesadillas into wedges and serve immediately.