To start, pre-heat your oven to 190 C Fan / 200 C Electric / Gas Mark 5.
To make the marinara sauce, start with dicing up the onion, carrots and garlic.
Next, heat the olive oil in a medium sized pan and add the onions, cooking for around 5 minutes or until they start to look golden. Then add the carrots, cooking for another 2 minutes.
Now add the garlic, thyme and chilli flakes, and cook for a further 2 minutes, stirring regularly.
Next, stir in the chopped tomatoes and slightly reduced the heat to medium-low and simmer uncovered for around 25-30mintues, stirring occasionally.
Once cooked, remove from the heat and set to one side.
For the pesto, put all the ingredients into a food processor and blend until everything is well mixed together, but still has a little texture. Then set to one side.
To make the mushroom and spinach filling, firstly, slice the mushrooms to around 1cm thickness. Then, heat the olive oil in a large pan over a medium heat, and add the mushrooms. Cook for around 2 minutes, while stirring regularly.
Next, add the spinach to the pan and fold it into the mushrooms, along with the salt. Continue cooking for around 3 minutes or until the spinach is wilted.
Now, remove the spinach and mushroom mix from the heat and stir in about 2 tablespoons of your pesto. Then set the mixture to one side.
For the tofu ricotta, start by adding the sunflower seeds to your food processor and blend them up into small pieces.
Next, remove any excess water from the tofu and add it to the food processor with the sunflower seeds. Then blend together until the mixture is almost smooth.
Place the mixture into a large mixing bowl, then stir in the olive oil, minced garlic, lemon juice, zest and salt.
Finally, add the nutritional yeast and give it a further stir, ensuring everything is well mixed together. Then place it to one side.
Once all your lasagne fillings are ready you can start putting everything together. First, get a 8x10-inch oven proof dish, then ladle about 1 cup of the marinara sauce into the bottom of the dish, spreading it out evenly. Then place a layer of lasagne sheets on top.
Next, add about a third of the ricotta mixture on top of the layer of lasagne sheets, along with one-third of the mushroom and spinach filling, spreading it out evenly.
Then spread 1-2 tablespoons of the pesto over mushroom and spinach filling, and then add another layer of lasagne sheets.
Keep repeating the above steps until the dish is full or you run out of ricotta and mushroom mixture. Then place a final layer of lasagne sheets on the top and cover it with the remaining marinara sauce.
Next, cover the dish with foil and place it into your pre-heated oven for 30 minutes. Then remove the foil and cook for a further 25-30 minutes.
Once cooked, remove the lasagne from the oven and leave it to sit for 10 minutes. Then top with the remaining pesto and serve. Enjoy!