Chop seitan and leeks, saute over medium high heat
In the meantime chop all other veggies (I use a food processor) until it is almost a puree. Add tomatoes last so it doesn't water down and make a huge mess if you do it on a board. Add Italian spices and a bit of dried veggie stock, as well as 2 tsp of agave syrup. Saute mixture for a few minutes.
Slice zucchini into thin slices.
Layer zucchini, seitan, veggie puree, zucchini, seitan, veggie.... you get the idea. End with a layer of puree
Combine cashew butter, a bit of dried veggie stock, nutritional yeast to taste and add the water to make it cheese sauce texture. Pour over your lasagne and bake for 25-30 min