What can I do to thicken the mixture in a meat "cup?" I've got a pound of ground beef in the refrigerator that I need to use by tonight, and have been eating pasta and hamburgers in unusual abundance lately so my usual standbys of ragù and patties are pretty much off the table.

While searching for recipe ideas I happened upon these barbecue beef cups - a bit heavy on the store-bought ingredients, but very convenient and looks palatable.  However, one of the reviewers pointed out that, even with various savoury additions, the final product came out more or less like a sloppy joe, and I'd prefer to have something less... sloppy.

In other words I'd like to make one of these so that the filling holds its shape and doesn't start leaking after the first bite.  On the other hand, I also don't want it to come out like a fruit tart with the consistency of jelly.  I keep thinking of those Jamaican beef patties you buy in stores and the consistency of the filling; it's relatively moist, but dry/solid enough to stay in the patty.

Can I accomplish this, preferably without the aid of exotic hydrocolloids?  I was thinking of mixing in an egg, but I'm not sure how well that would work or if it would be better to use the whole egg or just the yolk.  Tomato paste is another "thickener" that would seem to work well with this type of recipe, but might not get it thick enough before ruining the taste.  And of course I have various starches and baking ingredients but I worry that too much of those will just turn it into jelly.

Any tips/suggestions?
A little cornstarch should, if you add it with the bbq sauce, make it just thick enough to cling together a little better.

I'd say make a slurry of say 1/2c water, 1/4c bbq sauce, 1tsp cornstarch and add it to your ground beef. Let it cook down (I'm basically thinking how taco packets work here) until it's close to where you want it; continued heat in the oven should finish binding.

Or skip the bbq sauce, use dry herbs and spices mostly with just a tiny dab to bind it together.

Also you just made me want a patty, you awful man.