1 The first step to prepare our tuna and spinach lasagna recipe is to cook the lasagna pasta sheets with water and salt. Once they are ready we cool them with cold water and set aside. You can also do it with fresh pasta, so it will be cooked at the time of placing it in the oven.

2 In a bowl put the finely chopped onion and add the bell pepper, the chopped garlic clove and mix it. Once ready we brown them in a pan and when ready add the four cans of tuna, it is important that it is well drained to prevent it from burning. Once this mixture of onion, tuna, bell pepper and garlic is ready, set it aside and start with the spinach.

3 For the preparation of the spinach you will need a pot to boil it. Once ready, put in a pan with a teaspoon of oil a little onion to fry and then add the spinach well drained to let them sauté. Add salt and pepper to taste and set aside.

4 Next, begin to assemble the lasagna layers. First of all, remember to grease the baking dish with a little butter. Place the first sheets of lasagna pasta and spread the first layer of tuna, then another sheet of pasta and then the spinach layer. Repeat these steps until you run out of lasagna sheets.

5 Preheat the oven to about 180 degrees Celsius, while we prepare the homemade béchamel sauce to complete our tuna and spinach lasagna.

6 For the béchamel sauce you must heat butter and sauté in it the two tablespoons of flour, until it is a golden paste. Then gradually add the milk, add a touch of nutmeg, salt and pepper to taste and let it simmer while stirring until it forms a smooth cream.

7 Once we have finished our homemade béchamel sauce, we cover the lasagna with it. Add a layer of grated cheese for gratin and let it cook in the oven for about half an hour. We recommend that the last 10 minutes you put the oven on the gratin option so that the cheese is toasted.