1. Go up and smash the 4 blocks on the right side.
2. Bounce back down and smash these 3 blocks.
3. Start digging a cave into the heart.
4. Widen this cave and try to remove the X while going up.
5. You should destroy the two blocks on the right as well.
6. Use the X as a starting point for digging to the left.
Always try to smash blocks from the side while going up or down.
You can destroy the remaining blocks this way.
Reduce the GAMESPEED in the options menu if the room is too difficult.