Step 1

Stovetop method: Bring 1 inch of water to a boil in a medium saucepan. Reduce the heat to medium-low and place a bowl inside the pot to create a double boiler. (The bowl should be big enough to rest above the rim of the pot without the bottom touching the water.) Add both cheeses, the half-and-half, garlic, jalapeño, and ground black pepper, then stir to combine. Cook, stirring occasionally, for 5 to 10 minutes, until the cheese is melted and the dip is creamy. Stir in the green chilies.

Step 2

Slow cooker method: Combine both cheeses, the half-and-half, garlic, jalapeño, and ground black pepper in the base of a slow cooker, and stir to combine. Cover and cook on high for 50 minutes, stirring once half-way through. Stir in the green chilies. Transfer to a serving bowl or reduce the temperature of the slow cooker to warm and keep covered until ready to serve.

Step 3

Top with diced tomatoes, cilantro, and sliced jalapeño. Serve immediately.