Hey I came up with an idea I wanted to try for cookies, it'll be a filled cookie. The crust will be shaped like a bottle cap only bigger, with a flaky crust, inside, I want orange mousse. This is were the problem comes in. To finish off the cookie, I want to pour icing over it, and let it harden, almost like cinnamon roll icing. The problem is, Would the Mousse melt if I pour hot icing over it? And is there a way to make a sort of glaze-like icing, that will go on at room temperature and then set up? Any help would be appreciated.

look for a lemon glaze icing, or make a run-out of royal icing (make you're regular royal icing, after beating, remove from mixer and add a tablespoon of water at a time, slowly stiring in a figure 8 motion, until you reach the right pouring constancy.)

Yeah I would just use normal icing sugar mixed with water and whatever flavour/colour you want. You then just trickle it over and it'll harden.

Awesome guys, thanks!