Hey
BrianGSDTexoma
an easy way to make that sauce is to get some very very bland alfredo sauce in the jar and church it up with blender of green chili, a little cumin, some cilantro, onion, and a some chili powder.
Yeah it seems odd but those bland alfredo sauces are basically nothing but cream and light light amount of spices so they are easy to spin into a Tex/Mex cream sauce. I've seen this done and eaten it and it taste great and replicates the kind of sauce you describe (that I see in Tex/Mex joints).
Flour tortillas will be fine but expect them to come apart very easily, which is fine because it all kinda gets cut and chopped up as you eat it anyhow lol.
The key for me when using flour tortillas for enchiladas is to know that your sauce and veggies will produce liquid that separates making more liquid than you thank you have and that greatly adds to the detreating of the flour tortilla.
When I make the flour tortillas enchiladas I do them individually in the baking dish and keep this in mind when adding components that can produce liquid.
When making corn tortilla ones you can kind of just roll it all up and slop on all the sauce and everything else. Not the case with flour unless you just leave them flat and do a flour tortilla enchilada casserole back type thing. Same concept just no rolling and you expect it to all be mixed up as you serve and eat it.
Finally, when doing flour tortilla enchiladas I bake only long enough for the cheese to melt or I broil it sometimes. This also keeps the whole thing from becoming a mess from falling apart.
It will taste great whether it all falls apart on you or stays together and to me the flavor is what matters.
It's also easy to do 3-4 enchilada batches with different approaches to see what works best for you while using flour tortillas. Not hard to trail and error it over about 4-5 back to back meals because the taste is usually great no matter what :D