Marinate the fish fillet ( I have a small flounder) in lemon juice, salt and white pepper.
Boil the potatoes in their uniforms for 20 minutes, strain, pour cold water, then it was easier to peel. Let the potatoes cool. Peel and slice.
Finely chop the onion and garlic. Prepare spinach (fresh-rinse and shake from moisture, I have-frozen)
To prepare the sauce: flour, oil, milk, Gorgonzola (another blue cheese), sundried tomatoes ( I - ready, Basil garlic butter. If you have dried tomatoes without oil, they must be pre-filled with water and then squeeze, cut)
In a hot pan, heat 1 tablespoon of vegetable oil, fry onions and garlic (until transparent), add frozen spinach and 100 ml of water, simmer under the lid for 10 minutes, stirring occasionally. The excess liquid at the end of the drain.
If you cook with fresh spinach, then do not add water and reduce the quenching time to 3-4 minutes.
Season with ground nutmeg, salt and pepper.
First, we prepare the classic Béchamel sauce. I'll show it in more detail (for beginners), and those who know how to cook, you can skip a few steps.
Heat a saucepan with non-stick coating, reduce the heat, put the butter in it and when it is not yet completely melted, add flour. Then very quickly all the time interfere with a wooden spatula and keep ready milk and water (broth). When the flour and oil are fully connected and brewed a small lump of dough, gradually begin to pour slow portions of the liquid.
And continuously stir it into the oil-flour mixture.
The next portion of liquid (just after 5-6 rotations of the scapula) pour when the sauce leaves the sides of the dish (see photo). Gradually add water and milk until the sauce reaches the dough state as on pancakes.
Season with salt, pepper and ground nutmeg.
Add chopped dried tomatoes to the sauce.
Remove from heat. Add in the hot sauce and the Gorgonzola, stir to dissolve cheese.
Collect the gratin. Forms for baking grease with oil, put a layer of potatoes.
Fish on top.
The next layer is spinach - onion.
***You can add 1 more layer of fish fillet.
Again - put potato.
Pour the cooked sauce over the top.
Sprinkle with grated hard cheese (for crust).
Bake in preheated 200*C oven until Golden, about 30 minutes.