You have action points, which you can spend on special events marking as "????". These points restores every day to your current maximum amount. You can increase your maximum amount by buying "Time Management" in Shizuko's shop (it has 3 levels).

To obtain "hidden" recipes and desserts you need to use "????" in particular times of day and in particular room. "????" buttons aren't located in Shizuko's house and in other places outside sisters's house.
P.S. You can save before using "????" and load back if you haven't gained needed scene or item.

For example, you can use "????" in Shizuku's Room and gain info about her hobby (works only for her if not mistaken).
P.S. I've already know about hobby, so I obtain nothing on the screenshot.

In the morning I didn't find anything "hidden". Yeah... that's all this section about...

At noon enter the Living Room and use "????". You can obtain a recipe of "Thick Ramen".



If you are interested, by quality "Thick Ramen" equals "Sushi Combo" (can be bought in Shizuko's shop) = all three sisters will very like it.

In the Hallway you can find first "hidden" dessert - Hazelnut Mallow Pancake.



This dessert is item (adding into your Backpack). You can eat it or gift it to any women.
If you eat it you'll restore 100 energy, add 50 desire and relief some stress.
If you gift it to any woman she'll get 45 desire, her mood very likely improve and probably she'll get a lot of affection (I don't know because I maxed out every women's affection).
Ayano likes this dessert, so all effects by gifting it to her will doubled.

In the afternoon enter the Kitchen and use "????". You can obtain second "hidden" dessert - Chololate Chiffon Cake.



This dessert is item (adding into your Backpack). You can eat it or gift it to any women.
If you eat it you'll restore 100 energy, add 50 desire and relief some stress.
If you gift it to any woman she'll get 45 desire, her mood very likely improve and probably she'll get a lot of affection (I don't know because I maxed out every women's affection).
Shizuku likes this dessert, so all effects by gifting it to her will doubled.

In the Living Room you can find third and the last one "hidden" dessert - Fruit Sundae.



This dessert is item (adding into your Backpack). You can eat it or gift it to any women.
If you eat it you'll restore 100 energy, add 50 desire and relief some stress.
If you gift it to any woman she'll get 45 desire, her mood very likely improve and probably she'll get a lot of affection (I don't know because I maxed out every women's affection).
Kasumi likes this dessert, so all effects by gifting it to her will doubled.

In the evening enter the Kitchen and use "????". You can obtain a recipe of "Red Wine Beef Stew".



If you are interested, by quality "Red Wine Beef Stew" equals "English Roast Beef" (can be bought in Shizuko's shop) = all three sisters will be in culinary heaven.

Shizuko likes all three desserts, so if you'll gift her one of them she anyway get doubled effect boost.



You can obtain desserts unlimited amount of times. You also will gain "hidden" recipes again if all conditions are met (I don't know why develops did this).

Desserts don't mark in journal, but "hidden" recipes do.

This is my first guide, so it can be a bit scuffed in some places, but I hope that will help someone.
Thanks for reading!