Jalapeno Poppers and getting a thick crust?
I have found that the problem with thicker batters not adhering to peppers generally is to do with the outer membrane protecting the flesh of the jalapeno. Essentially, you need to try to remove or weaken its effect. 

You can minimize the effect of the membrane by:


roasting the pepper, then steam in a brown paper bag and remove it
scoring the membrane with a fork 


Also, the pepper may have a decent layer of wax on it; this you can try to wash off with hot water and a thorough scrubbing.