Peel and chop the apples. You will need 1 kg of apples after they're peeled. I used sweet Gala apples which are my favourite for this dish.
Make medjool date paste by combining medjool dates and 100 ml of water in a food processor. Mix on high speed for a few seconds. Scrape the mixture and mix again a little bit.
Transfer apples to a large pot. Depending on what variety of apples you are using you may need to add some water. I didn't need any. Be careful to not put too much water though. If there's too much water left in the pot you will have to cook the apples for longer and they will become too soft.
Add to the same pot also 1 tsp of cinnamon, 1/4 tsp of vanilla and half of the medjool date paste. Mix together.
Cook the apples on medium heat for 10 min until they become softer and most of their liquid evaporates. Open the lid a little bit after the water from the apples stars boiling to allow for faster evaporation.
Crumble walnuts with your hands and mix them into the cooked apples.
Transfer the apples to a greased baking dish (I used 23 cm round baking dish) and spread them equally.
Put almonds, oats (if you are using very soft oats as I am, it's important that you put almonds in the food processor first), 1 tsp of cinnamon, 1/4 tsp of vanilla, the other half of medjool date paste and melted coconut oil into the food processor. Blend together and press the mixture down with a stick. Leave some almond chunks in there for a crunchier crumble.
Transfer the crumble onto the top of the apples and arrange it equally.
Bake at 180 °C for about 20 min. It's done when the top becomes dark brown.
Serve warm with a scoop of vegan vanilla ice cream.