For making things taste good, learning how to use spices can really help. With a surprisingly small number of spices, you can mix up the taste of chicken, for example. Cumin and cilantro both work for Mexican, Indian, and others, for example. Basil works for both Italian and Southeast Asian (yes, it's not exactly the same basil, but it can be close...) Having a good core of spices in your cabinet frees you up considerably.
If you like Indian food, there are a very wide range of flavors available. I got introduced to it a long time ago with a cookbook from Madhur Jaffrey - she makes it accessible to westerners, and once you get into it, you can take things as far or as simple as you want. The options help keep things from getting boring, and if you like tinkering, it gives you mental challenges that can be fun.
Peanut butter sandwiches aren't shortcuts. They are a carb and fat source like rice and potatoes.
Definitely consider having more than one piece of toast at breakfast.
Shredded cheese is a game changer can melt over so many different things tacos, burgers, pizzas, pasta. If your worried Bout fat content you can get the skim cheeses use lean meats. You'll be able to eat heaps of the above mentioned foods.
Ylutibe cooking channels to look at are Adam Ragusea and even Alan Thrall cooking vids have some value.
I live off shredded cheese. Lucerne and Kraft make fat free mozzarella for those trying to minimize fat gain or cutting weight.
Yes for those in Australia beqa does a 50% less fat cheddar shredded or sliced that packs 34p 15f 0c per 100g. It does have bit of a vintage taste to it though.
I can't give advice on how to eat more. There are already many others commenting who are better for that job. I can, however, give a recipe that is very calorie dense and really hard for me to stop eating. I swear I'd eat an entire pig trough of the stuff if given the chance. It's the Food Wishes take on chicken tikka masala.
Food Wishes link: Food Wishes Video Recipes: Chicken Tikka Masala – God Save the Curry
We generally skip the cilantro. Also, we do the coconut cream option (instead of heavy cream) because my wife is lactose intolerant. Both are absolutely delicious. The coconut cream might not make you feel quite as full, I don't know. You can also titrate your carbs by adjusting how much rice you serve with it. The sauce has enough flavor that you really don't even notice the rice.
The batch in the recipe is for four servings. We double or triple the batch and pray we have enough restraint for leftovers.