Make the caramelized onions first. In a large non-stick skillet, heat the vegan butter or olive oil on medium high. Then add the sliced onions.
Saute, for a minute or two, then press the onions down into the pan in a thin layer. Reduce heat to medium, you can reduce more if needed, and let them saute without disturbing them for about 5 minutes. Then toss and press them back down into the pan again and leave for another 5 minutes. Repeat until they start to brown.
Then drizzle the onions with the agave and a pinch of salt. Toss to coat the onions and continue to saute the onions until they are completely golden brown. The whole process takes about 25-30 minutes. Remove from heat.
While the onions are caramelizing, make the ricotta. Drain the tofu and just using your hands, squeeze as much liquid out of the tofu as you can over the sink. Then add the tofu to a food processor or blender.
Then add the nutritional yeast, the lemon juice, 2 tablespoons of the non-dairy milk and a few pinches of salt and pepper. Pulse the mixture on high until it is nice and smooth. If you are having a hard time blending, add the extra tablespoon of milk. Set aside.
Next make the thyme bechamel. You can either wait until the caramelized onions are done, and use that same skillet once you remove the onions, or use another large skillet.
Heat the vegan butter on medium high. Once it has melted, whisk in the flour to create a roux. Let it simmer for a minute, then add the non-dairy milk. Whisk thoroughly making sure there are no lumps of roux left. Then bring to a simmer and reduce heat to medium low.
Whisk constantly, until nice and thick, about 2-4 minutes. Then stir in the thyme, nutmeg and a few pinches of salt and pepper. Let simmer for another minute. Then turn off the heat, but leave on the stove until ready to use to keep it hot.
Once the onions, ricotta, bechamel and lasagna sheets(either oven ready, or you have already cooked them according to package directions) are ready, preheat the oven to 375 degrees(F).
Layer the lasagna. Using 4 ramekins, 2 small baking dishes(I use 5 inch round dishes), or a smallish baking dish(7 inch).
Depending on how many baking dishes you are using, make sure you divide the filling accordingly. First add a thin layer of bechamel sauce on the bottom of the baking dish. Then cover with lasagna sheets. I cut them with kitchen scissors to fit if necessary.
Then spread that with the ricotta mixture, then spread a thin layer of onions on top of that, then sprinkle with a layer of vegan mozzarella, then drizzle with more bechamel. Repeat, the process, you should be able to do that for 5 layers. Then the last layer, place lasagna sheets on top, spread generously with the bechamel, then sprinkle with more mozzarella and a bit more onion.
Bake for 25-30 minutes or until hot, bubbly and brown. Serve.