Dart nested collections - List<Map<String, Object>> - dart

Question

I did a little Basic and Ada programming 25 years ago, but never got any deeper ... now my mind isn't as sharp as it used to be so I bought a few courses about Dart and Flutter on Udemy, but instructors don't really teach programming... They start advanced topics like complex data structures in the first lessons in 3 minute long video and I'm completely lost.
I'm trying to make some sense on my own about nested collections, researching on the internet, but i can't figure out how to access double nested collections (list/maps inside a list of maps). Can you guys share some links / courses on the topic.
Here is some sample code, I managed to access to the first map data, but I don't know how to get the items in the 'ingredient' list, neither the data in the 'macros' map... How can i now the 'protein' in my dishes? Thanks in advance.
void main() {
var recipes = [
{
'name': 'Hoisin Chicken Lettuce Cups',
'type': 'Salad',
'ingredients': ['mango', 'hoisin sauce', 'chicken breasts', 'romaine lettuce', 'cress'],
'calories': 289,
'macros': {
'fat': 9.6,
'sat_fat': 1.8,
'protein': 31.3,
'carbs': 20.3,
'sugar': 19.2,
'salt': 1.3,
'fibre': 2.5,
},
},
{
'name': 'Smoked Salmon Plates',
'type': 'Salad',
'ingredients': ['cucumber', 'dill', 'smoked salmon', 'avocado', 'cottage cheese'],
'calories': 246,
'macros': {
'fat': 17.7,
'sat_fat': 3.9,
'protein': 17.1,
'carbs': 4.4,
'sugar': 3.2,
'salt': 1.5,
'fibre': 1.2,
},
},
];
// Managing to accest collection data... How to get protein amount?
// How to know 'macros' lenght? ...
print(recipes);
print(recipes.length);
print('---------------------------------------');
print(recipes[1]);
print(recipes[1].length);
print(recipes[1]['ingredients']);
print(recipes[1]['macros']);
print('---------------------------------------');
}