Baking – Storing Self-Made Cookies/Brittles/etc longer: ingredients and techniques

I have the same preference. Three things that work for me:

(1) If you are using any vegetables, saute them to get as much liquid out as possible in advance. For spinach or other greens, actually squeeze the water out using a tea towel or potato ricer.

(2) Use less sauce or make the sauce thicker. You can accomplish the latter by starting with thicker ingredients (tomato puree vs. chopped tomatoes), or by reducing it on the stovetop somewhat first.

(3) For ricotta fillings, indeed add a couple of eggs to help them setup.

Here is my spinach and ricotta lasagna recipe, which as you can see from the picture, sets up very firm and sliceable. And I've also got a summer squash and portabello mushroom lasagna which illustrates points 1 and 2.

Last summer was a long time ago. The National Center for Food Preservation has this to say about herbs in oil:

Oils may be flavored with herbs if they are made up for fresh use, stored in the refrigerator and used within 2 to 3 days. There are no canning recommendations. ... Pesto is an uncooked seasoning mixture of herbs, usually including fresh basil, and some oil. It may be frozen for long term storage

Clostridium botulinum is a serious enough hazard with oiled herbs that I'd not trust a dash of lemon juice on top of the oil to protect me from getting sick after 9 months storage. You're much safer freezing the stuff as recommended. Ice cube trays produce nice pesto cubes that you can store safely in a freezer bag for at least a couple years.