Lightly coat the inside of a 4- to 5-quart slow cooker with nonstick cooking spray if desired for easier cleanup.

Pour the Rotel tomatoes into a fine-mesh strainer and let them drain thoroughly. Press lightly with the back of a spoon to remove excess liquid without crushing the tomatoes.

Spread the 4 cups (560 g) shredded cooked chicken evenly over the bottom of the slow cooker.

Scatter the cubed cream cheese over the chicken: Add the sour cream, Buffalo sauce, drained Rotel, ranch seasoning, and garlic powder.

Cover and cook on LOW for 1 hour 30 minutes. The cream cheese should be very soft around the edges and beginning to melt.

Remove the lid and stir thoroughly, breaking up any remaining cream cheese pieces. The mixture should become thick, creamy, and evenly orange-red.

Cover and cook on LOW for another 30 minutes, until the mixture is hot throughout.

Stir in the cheddar and Monterey Jack until evenly distributed.

Cover and cook on LOW for another 20 to 30 minutes, stirring once halfway through, until the cheese is fully melted and the dip is smooth.

Stir well and check the center with an instant-read thermometer. Since the dip contains previously cooked chicken, it should reach at least 165°F (74°C) before serving.

If the dip seems too thick, stir in 1 to 2 tablespoons (15 to 30 ml) of milk at a time until it reaches a creamy, scoopable consistency. If it seems thin, leave the lid slightly ajar and cook for another 10 minutes.

Switch off the slow cooker and let the dip stand for 10 minutes. It will thicken slightly as it settles.

Top with green onions, crumbled blue cheese, or an extra drizzle of Buffalo sauce if desired.

Use the WARM setting for serving, stirring occasionally: Do not leave the dip at room temperature for more than 2 hours.