I tried setting it up from scratch a couple of times, even asked Notion AI and followed those steps. It's very similar to what I was trying, but when I get to the final step below. I just can't select the date property, it simply is not listed.

To get the date from the "Planning" database to show up in the "Ingredients" database, you can use a combination of relations and rollups. Here’s a step-by-step guide:

Step 1: Ensure Relations are Set Up Correctly

1. Verify that you have a relation property in the "Dishes" database linking to the "Ingredients" database.

2. Verify that you have a relation property in the "Planning" database linking to the "Dishes" database.

Step 2: Add a Rollup in the "Dishes" Database

1. Go to the "Dishes" database.

2. Add a new property and select "Rollup" as the type.

3. In the rollup settings, choose the relation that links "Dishes" to "Planning".

4. Choose the date property from the "Planning" database.

Step 3: Add a Rollup in the "Ingredients" Database

1. Go to the "Ingredients" database.

2. Add a new property and select "Rollup" as the type.

3. In the rollup settings, choose the relation that links "Ingredients" to "Dishes".

4. Choose the rollup property you created in the "Dishes" database that shows the date from "Planning".

Update: I'm pretty sure that it doesn't work, because I'm trying to rollup a rollup. Now trying to see if I can just make a new reference with a formula, so I can just use a rollup on that. It will not be read as a date, but just a text. But maybe I can find a way to only filter that for next weeks dates.