01 - Using a hand mixer or whisk, beat the softened cream cheese, granulated sugar, vanilla extract, and sour cream in a medium bowl until completely smooth and creamy, approximately 2-3 minutes. Ensure no lumps remain.
02 - Arrange the flour tortillas on a clean work surface. Spoon approximately 2 tablespoons of the prepared cheesecake filling onto the lower third of each tortilla. If using berries, scatter 1 tablespoon evenly over the filling.
03 - Fold the left and right edges of each tortilla inward toward the center, approximately 1 inch. Roll the tortilla tightly from the bottom up, creating a compact burrito shape. Secure with toothpicks through the seam if necessary to prevent unrolling during frying.
04 - Pour vegetable oil into a deep skillet or heavy-bottomed saucepan to a depth of 2 inches. Heat over medium-high heat until the temperature reaches 350°F as measured by a kitchen thermometer.
05 - Carefully lower 3-4 chimichangas into the hot oil, seam side down. Fry for 2-3 minutes per side, turning once, until deep golden brown and crispy throughout. Remove with a slotted spoon and transfer to a paper towel-lined plate to drain excess oil.
06 - Working quickly while the chimichangas are still warm, brush each fried pastry generously with the melted unsalted butter using a pastry brush. This helps the cinnamon sugar adhere to the surface.
07 - Combine the granulated sugar and ground cinnamon in a shallow bowl, mixing thoroughly to distribute the cinnamon evenly. Roll each buttered chimichanga in the mixture, pressing gently to ensure complete coverage on all sides.
08 - Arrange the finished chimichangas on a serving platter. Serve immediately while warm and crispy. Optional garnishes include whipped cream, additional fresh berries, or warm chocolate sauce for dipping.