01 - Using a hand mixer or whisk, beat cream cheese and granulated sugar in a medium bowl until completely smooth. Blend in sour cream and vanilla extract until fully incorporated and creamy. Set aside.
02 - Lay tortillas flat on a clean work surface. Spread approximately 2 tablespoons of cheesecake filling across the lower third of each tortilla. Add 1 tablespoon of diced berries if desired. Fold both sides inward toward the center, then roll tightly from bottom to top to form a sealed burrito shape. Secure with toothpicks to prevent unraveling during frying.
03 - Pour vegetable oil into a deep skillet or saucepan to reach 2-inch depth. Heat over medium-high heat until oil temperature reaches 350°F. Use a kitchen thermometer to verify temperature.
04 - Carefully place 2-3 chimichangas in hot oil, seam side down. Fry for 2-3 minutes per side until deep golden brown and crispy throughout. Remove with slotted spoon and transfer to paper towels to drain excess oil. Repeat in batches, maintaining oil temperature.
05 - Brush each warm chimichanga generously with melted butter. Combine granulated sugar and ground cinnamon in a shallow dish, mixing thoroughly. Roll buttered chimichangas in cinnamon sugar mixture, pressing gently to ensure even coating on all sides.
06 - Arrange chimichangas on serving platter. Serve warm while coating remains crisp. Accompany with whipped cream, fresh berries, or chocolate drizzle if desired.