Calling all plant and flower sleuths

See this tree?

This tree has been here for about ten years . . . a client mailed it to us from Minneapolis, all wrapped up and about twelve inches tall. (It's grown a little.)

We planted it, watered it, and named it Minnesota, for obvious reasons.

We didn't know that Minnesota would bloom.
But he did bloom this year!

Now, here are your clues. You have the picture of the tree up there, and the leaves look like this:

And here are the gorgeous flowers:

But what is Minnesota???? What kind of tree?

I haven't a clue. I guess I used to know. But hopefully one of y'all can tell me?

Love,