Roast tomatoes in parchment-lined pan in a 400-degree preheated oven for 15-20 minutes.
Meanwhile, dice the onion and finely chop the garlic cloves.
Sauté the onions in a drizzle of olive oil until softened.
Add garlic to the pan with the onions and cook for an additional 30-60 seconds.
Add most of the garlic and onion mix to a blender or food processor, leaving about ¼ of it in the pan.
Add cream cheese, milk, cheese and salt to the same pan with the remaining garlic and onion mixture.
Melt over medium heat, stirring occasionally.
Remove the roasted tomatoes from the oven and add them to the blender or food processor along with the onion and the garlic. Add in the canned chipotle peppers (minus the sauce; save it for later if you love spice!). Blend!
Add the blended tomato mixture to the melted cheese and stir well.
Time for a taste test! Add a pinch more salt if necessary, along with any spices you like (cumin, Mexican oregano, etc.). The sauce from the canned chipotles can be added at this point, as well for more heat. Add more cheese if the dip is too thin to cling to chips.