If you are using fresh peas, boil some salt water on high heat, and throw in the peas for about five minutes. If you are using canned peas, just drain them.
Peel the potatoes and slice them about 1/3 of a centimeter thick. If you do this step well ahead, put the potato slices in some water, so that they don't oxidize. It is generally a good idea to soak potatoes in warm water before cooking, so you get rid of the starchy flavour and texture.
Cut the chicken into byte-sized pieces. All you computer geeks out there, no, a chicken is not a pile of bits, byte-sized means small enough to put in your mouth all at once.
Chop the garlic very finely. Do not crush it, crushing leaves you with too big chunks and you lose the juice. No shortcuts, take five minutes and chop the bastard finely.
Slice the mozzarella
This dish isn't very juicy. Though it is not dry, there is not enough liquid in it to distribute the salt evenly between the ingredients. Therefore you have to salt everything. Salt the potatoes, salt the beshamel sauce, salt the meat and the peas. Now, if you are salting everything, it is really easy to oversalt. And if you are afraid of oversalting it's really easy to undersalt. Now, that I have messed with your head, my instruction for salting is: Salt everything to taste. I am a bastard, aren't i?
You are going to have to fry the garlic in oil. It's really easy to burn. If your garlic gets dark brown or black at the edges, throw everything away and start over, you haven't gotten very far anyway and you used only the oil and garlic. I'm being serious here, burned garlic will destroy your dish. Throw it away and start over.
Put curry, cumin and some salt on the chicken pieces and mix well. Melt a small amount, maybe 20g of butter in a pan. Set heat to low-medium Add the garlic and fry it in butter for one to one and a half minute. Throw in the chicken pieces in the pan and brown them on all sides. Set aside for later use.
For the beshamel sauce, heat up the milk. You can use a microwave oven for this or whatever you want, just make the milk hot. Melt 70% of your remaining butter (leave about 30 g for later) in a saucepan. Turn the heat to medium. Add all of the flour and stir. Keep stirring for about a minute. Set the heat to low. Add the hot milk and keep stirring until all the lumps have dissolved in the milk. Take the sauce off the heat. Add some salt and grind some nutmeg into the sauce. Coll the sauce down until it's lukewarm. Add the eggs and stir vigorously, so that the eggs blend into the sauce well.
Take an oven-proof glass pot or a deep tray. Do not use a ceramic pot, because ceramics is an insulator and it will distribute heat unevenly, so you will end up with an unevenly cooked dish. Grease the pot with the remaining butter. Completely cover the bottom of the pot with potato slices. Sprinkle some of the chicken pieces over the potatoes. Sprinkle some of the peas over the chicken. Pour some beshamel sauce over the peas. Make sure you use proportionate amounts of everything. You must start and finish with a layer of potato slices, so you need to proportion it differently then other ingredients. For example, if you used 1/4 of potatoes to cover the bottom of the pot, then you need to use 1/3 of meat, peas and beshamel. Season with some thyme and freshly ground black pepper. Mind you, even if you don't like spicy food, do add some pepper on each layer, the pepper gives the dish a very special aroma and flavour. Repeat adding layers of everything until you run out of ingredients. Make sure you end with a layer of potato slices.
Cover the pot. If you don't have a lid, use tin foil or something similar. Heat the oven to 200°C. Put the pot into the oven for 45 minutes. After 45 minutes, take the pot out of the oven, remove the lid and add the mozzarella slices on top. Return the pot into the oven for about 15 more minutes. By this time, the potatoes should be well cooked and the mozzarella should have a mice brown layer on top. Take the pot out of the oven and serve.
Enjoy your meal ;)