Soften your veggies. Add 1 tablespoon of olive oil to your pan or skillet, and set it over medium heat. Add the finely chopped carrot, celery, onion, crushed garlic cloves and 1 teaspoon of salt. Cook, stirring, for about 5 minutes, until the vegetables start to soften and change colour (the onion will look a little transparent and the carrot will look more muted in colour).
Brown the ground beef. Add your ground beef, then break it up with a wooden spoon or a spatula. Cook your beef, stirring occasionally, for about 5 minutes, until it's brown all over.
Add the sauce ingredients. Pour in your tomato passata (puree), 1/4 cup tomato paste, 2 teaspoons of fish sauce if you're using it, 1/4 cup of red win and your chopped rosemary. Stir, then reduce the heat to low and let the sauce simmer for 10 minutes, until it's reduced slightly and starting to thicken up (it should still be quite saucy).
Add your lasagna sheets. After 10 minutes, snap your lasagna sheets in half and carefully nestle them amongst the bolognese sauce. Try to arrange them all around the pan, pushing some a little further down into the sauce so they're well dispersed. Spoon a little of the sauce over the sheets so that they're at least just submerged in the sauce (this will help them cook), then pop the lid on your pan (or use a wooden board/large dinner plate) and cook over low heat for another 10 minutes.
Mix your ricotta sauce. While the lasagna sheets are cooking, heat your broiler (grill) to 250C/480F. Then mix 1 cup of ricotta with 1/2 cup of parmesan in a small bowl. After 10 minutes, remove the lid from your pan. The lasagna sheets should be 'al dente' at this stage (cooked, still with a little bite to them). Spoon the ricotta and parmesan mix all over the top of your pan, smoothing it out so that it reaches around the edges. Scatter over the mozzarella, then transfer to the oven, to broil (grill) for 5 minutes, or until the sauce is golden, charred and bubbling.
Garnish and serve. Carefully remove the pan from the oven, then dollop over the basil pesto if you're using it and scatter with the basil leaves. Divide between plates, and dig in.