Translation:I'm making a walnut tart for the afternoon snack.
No. You usually use the plural when the dish contains a fair amount of a given ingredient, and the singular when it's only flavoured. (There may be exceptions).
Plus, in french à la noix (singular) means cheap, or bad quality.
→ Une tarte aux fraises
→ Une glace à la fraise
Who are we?
There are many in the UK who enjoy afternoon tea - some at home, some as a special treat in a tearoom etc.
Many tourists enjoy sampling an English tea with sandwiches, cakes, scones etc - "Afternoon Tea at the Ritz" - a very British experiience is what they advertise! For the wealthier tourists though!
In Scotland, I certainly had a :snack" when I got home from school - many years ago - until dinner was served!
Afternoon tea, taken between 3 and 5 pm, started in the 1840s by the wealthier social classes.
I think Duo should offer "aftrnoon tea" as an alternative.