I used to fly MKE-YYZ on an almost weekly basis. The 1:25 connection should be more than enough time, including a small buffer for slight delays.
If you misconnect in YYZ there may be other options to connect on later ex-YYZ flights (via other EU cities) that could get you in to MUC later than planned, but better than planning a 1/2 day in YYZ.