A concrete to me is a frozen custard blended at high speed with mix-ins like bananas, shortbread cookie, etc.
I'm aware there are a number of frozen custard places in southeastern Michigan, particularly in my neck of the woods in Oakland county.
Do any of these places make concretes? If so, who makes 'em best?
I like Ritter's. I'm not sure if they call them "concretes" but they do the mix-ins and hand them to you upside-down (which is the only way to serve them imo). There are only 3 locations in Michigan. I've been to the one on 8 Mile and Orchard Lake.
Just an anecdote, there is a tiny ice cream stand across from the Ingham County Fairgrounds in Mason, Michigan called Dairy Hill. They got threatened by DQ for calling their mix-ins Blizzards, so they've changed the name to Blysserd. Love it!