Step 1: Place the OREO cookies in the freezer for at least 30 minutes. This helps them firm up and prevents the cream from melting too quickly during frying.
Step 2: In a medium bowl, whisk together the pancake mix, milk, and egg (if using) until you have a smooth, thick batter. The batter should be thick enough to coat the back of a spoon and cling to an OREO without dripping excessively. Adjust with a tablespoon more milk or pancake mix if needed.
Step 3: Pour the frying oil into a deep pot or Dutch oven, ensuring it is 2-3 inches deep. Heat the oil over medium-high heat to 350-375°F (175-190°C). Use a candy/frying thermometer for accuracy.
Step 4: Using a fork or tongs, carefully dip each chilled OREO cookie into the batter, making sure it is fully coated. Allow any excess batter to drip off.
Step 5: Gently place 2-3 battered OREOs into the hot oil. Do not overcrowd the pot, as this will lower the oil temperature and result in greasy fried Oreos. Fry for 2-3 minutes, flipping once, until they are golden brown and puffed up.
Step 6: Carefully remove the fried OREOs from the oil with tongs or a spider skimmer and transfer them to a wire rack set over paper towels to drain any excess oil.
Step 7: While the fried OREOs are still warm, generously dust them with powdered sugar. Repeat the process with the remaining cookies, ensuring the oil temperature stays consistent between batches.
Step 8: Serve immediately and enjoy your homemade fairground treat!