MATE IN 3 MOVES (MEDIUM)

that's easy to checkmate,

medium to find the first move of the specific puzzle

hard for black to avoid checkmate

I don't know how to set the variation for the last move.

Hard for me anyway, I didn't get it.  I tried Qh2 thinking Ra2 Qh1 but for example if black plays simply Rh2+ there is no mate on the move.

I guess you have to see the Nf7 pattern, but it's a trick because your queen is in the way :)

Foolish to sacrifice the queen there.  Too obvious.  Why not move the queen in below your king, then move the king out of the way, checkmate in two moves.

Foolish is what you are saying! Pay more attention to the black possibilities of response and you'll realize it's not possible! Analyze the puzzles better before saying silly things!

Ps: All the puzzles I post make sense and has the most logical moves!!!