The technique of blending whole unpeeled garlic with lemon to make tahini sauce was something I read in Michael Solomonov's Zahav. With this much garlic you'd think it'd be overwhelming, but don't worry, it stays quite mild due to blending it in the lemon juice.
The Food Lab's Ultra-Gooey Stovetop Mac and Cheese
What we've got here is a stovetop mac and cheese recipe that's only about 10 percent more cumbersome to make than the blue box (the only extra step is measuring a few ingredients) but tastes far, far better.
The Food Lab: How to Make Chicken Tikka Masala at Home - we'll have to find this coconut milk yogurt folks mentioned in the comments or another non-dairy yogurt substitute, but this would be yummy for the retreat!