Flourless cookies form "skin" that seals in moisture

I've developed a sort of recipe for flourless low-cal cookies which, so far, actually works pretty well, resulting in a soft scone-type confection, but I'm having one problem with it: upon baking, the outside of the cookie everywhere except where it contacts the bottom cooks into a sort of skin which seems to keep moisture on the interior from cooking out, so the inside of the cookie stays much more moist than I would like. The recipe actually uses cabbage which has been ground to a rice consistency and wrung out as its base. The recipe for the batter in a batch size that made three pancakes and five large scones was:

• Cabbage prepared thusly, between 1/4 and 1/3 large head,
• 4 egg whites,
• 1/3 cup pumpkin puree,
• 1/3 cup almond milk,
• Just over 1 tsp glucomannan,
• 2 tbsp water,
• Spices and extracts,
• Stevia/erythritol blend for sweetness

To bake the cookies, I put "blobs" of them(~3-4 tbsp each I think) on parchment paper which had been sprayed with cooking spray, preheated an oven to 410 F, then lowered the heat to 375 once the tray was in the oven. I left it like this for ~30 minutes before lowering the heat to 270, then after another 15 minutes lowered it to 230, and they cooked for one hour in total. So back to my question: how can I cook out more moisture from the interior of the cookies? Would I want to skip the higher-temp. earlier stage, or maybe go for even more of a low-temp long-time method? Would puncturing them like with a fork after they're part-way cooked help? Maybe adding baking powder to the recipe? Or would reducing the liquid used in the recipe achieve this?