Heat oil in a large saute pan over medium high heat. Add the corn and cook until slightly charred, about 3-5 minutes. Add the jalapeno and garlic and continue to cook for another 2-3 minutes. Season to taste with salt and pepper, remove from heat and set aside to cool.
In a large bowl, stir to combine the refried beans with the taco seasoning. Place in a 9x13 glass baking dish, spreading into an even layer. Top with white queso, spreading into an even layer. Top queso with shredded lettuce, then olives, corn and then pico de gallo.
Spread the guacamole in an even layer over the top. Place sour cream in a piping bag fitted with a small piping tip.
To make the flag topping, draw a box with the sour cream in the top left corner of the dip. Pipe the sour cream into 6 lines to make the white stripes of the flag. Sprinkle the cojita cheese over the stripes. Use a small spoon and carefully make 7 red stripes of the flag with the salsa.
Fill in the box in the top left corner in with sour cream, spreading with a small offset spatula or knife into an even layer. Top the sour cream with crushed blue corn tortilla chips. Pipe the sour cream in dots on top of the crushed chips. Serve dip with red, white and blue tortilla chips.
In a medium saucepan over medium heat, whisk to combine evaporated milk, whole milk and cornstarch. Bring to a simmer, then slowly whisk in american and cheddar cheeses until melted and smooth. Whisk in the diced jalapenos and season to taste with salt. Set aside to cool.