Let’s get, ahem, into the difference between these two sets of words.

Into means movement, as in We headed into the restaurant.

In to, however, means nothing; the two words actually appear coincidentally together in a sentence, as sometimes they are part of other, adjacent constructs. For example, in might be part of a verbal phrase, such as drive in, while to is part of an infinitive verb like to pick up, and hence the sentence I’ll have to drive in to pick up some ice cream for the cake.

The easy way to remember the difference is to ask if in and to modify other words in the sentence. If they do, then use in to. Otherwise, into is the right call.