Brown 2 pounds ground beef in a large skillet over medium-high heat, breaking it up as it cooks. Drain grease.
Add 2 packets taco seasoning and 1 1/2 cups water (or amount specified on your seasoning packets) to the beef. Reduce heat and simmer until sauce is thickened, not watery. Remove from heat.
Spray slow cooker with nonstick cooking spray.
Spread 16 ounces cream cheese, softened in an even layer on the bottom of the slow cooker.
Add the taco beef mixture on top of the cream cheese, spreading evenly.
Pour 16 ounces salsa over the beef layer and spread to cover.
Sprinkle 2 cups shredded cheddar cheese evenly over everything.
Cover and cook on HIGH for 1 1/2 hours until hot and bubbly.
Top with 1 Roma tomato, diced and 2 green onions, sliced.
Switch to warm setting. Serve directly from slow cooker with tortilla chips.