Hi there - you can indeed make sub-categories, by assigning a "Parent" category to the sub-category. You'd can do that under Posts > Categories:
When you add the new sub-category, just assign it a parent by choosing an existing category from the drop-down menu under "Parent."
In terms of your Recipes page, you could try experimenting with this shortcode:
You could adapt it as needed to display your categories and sub-categories in whatever order you like.
Here's a guide to using that shortcode:
So for example, if you wanted to include a list of your Dessert posts, you would add the shortcode to your page:
The bit next to the word "category" needs to match your category "slug" - defined here in the "slug" column.
If you need further help, just let me know.