That's a rather recent development, but the word caffè still exists with that meaning, although nowadays it's generally used for a rather elegant bistrot-patisserie.
In fact the oldest joke (read: lame pun) in the book is "Un uomo entra in un caffè." [dramatic pause] "Splash"...
I don't understand this sentence much. Is it supposed to be something similar to "ho il gelato nel mio ristorante", or "il gusto di mio gelato è caffè"? I would also like to know if these examples, if I can call them like that, are correct in Italian since I'm trying to put things I learned into use. :) I'm still having trouble with what does ''al'' mean. Is it the same as ''nel''?
It means "I have coffee ice cream." Just like "I have vanilla ice cream"
In terms of the rest of your question, it is pointless to ask for 1-to-1 mappings from Italian prepositions to English prepositions. "Nel" can mean "in the," and "al" mean "to the," but "al can also mean "at the" or "made with." You just have to use these, and after a while you get a sense for it. (We have the same ambiguities in English, you are just used to them: think about the differences between being "in New York", "in love", "in a car" and "in line for the presidency." And why are we "in a car" but "on a train": we don't ride on the roof of trains!
Nick i think your comment needs to be pinned in the lessons for prepositions! But it's a very useful advice in general. I made huge a huge leap in my learning about a year ago when i finally realized this. You slow yourself down if you try to find the 1:1 "exact translation" because it just doesn't exist. Instead accept that your native language does the same and you just picked it up over time, and you will do the same for a new language eventually :)
From what I've been able to figure from the other comments, the primary meaning of "Io ho il gelato al caffè" is "I have coffee-flavored ice cream" although an uncommon secondary meaning could be "I have ice cream at the café".
As for "al" vs "nel" (and bear in mind that even between closely related languages, prepositions very rarely map perfectly one-to-one in usage because of the differences in idioms and relational metaphors), "al" is more like "to/at the" and "nel" is more like "in the".
With regard to food, idiomatically, X "al" Y more often than not means "Y-flavored X". So "gelato al caffè" is "coffee-flavored ice cream" and "bistecca al pepe" is "steak seasoned with black pepper" and "crema al cioccolato" is "chocolate-flavored custard".
More like "caffè freddo," where "freddo" is a proper adjective describing the temperature of the coffee.
(For everyone, not just BlakeGoodman08) "gelato al caffè" is "ice cream that tastes like coffee". "Caffè" is a noun. It's a key ingredient/feature of the ice cream. "al" is just the idiom in Italian for expressing the particular relationship between the coffee and the ice cream, or the chocolate and the cream, or the strawberry and the cake. English permits nouns to syntactically behave like adjectives (strawberry cake vs frozen cake) but Italian does not.
Basically, in Italian, you don't say "caffè gelato". Just like in English you don't say "ice cream of coffee".
In English, we say "flavor food", such as "coffee ice cream" or "strawberry pie".
In Italian, they say "food to the flavor", such as "gelato al caffè" or "torta alla fragola".
"gelato" is ice cream. "mocca" is coffee with chocolate in it...https://www.encyclopedia.com/education/dictionaries-thesauruses-pictures.../mocca
So, you need to say it's "coffee ice cream".