Preheat the oven to 350°F (176°C) and turn the muffin tin upside down.
Cut tortillas into 4-inch circles using the cookie cutter, about 3 circles per tortilla.
Brush the cut circles with melted butter and press them into the inverted muffin tin to form taco shells.
Bake the shells for 5-6 minutes until edges are lightly browned, then remove and cool in the tin.
In a shallow bowl, mix graham cracker crumbs, Christmas sprinkles, and crushed candy canes.
Melt the white chocolate using a double boiler or microwave, stirring constantly until smooth.
Brush the cooled taco shells with melted white chocolate, then coat them in the graham cracker mixture and refrigerate to set.
Beat softened cream cheese, powdered sugar, and vanilla extract until smooth.
Add heavy whipping cream and beat until the mixture thickens to a cheesecake filling consistency.
Fill a piping bag with the cheesecake mixture and pipe it into the chocolate-coated taco shells.
Garnish with additional Christmas sprinkles, crushed candy canes, and optional M&Ms before serving.