Simple Subtract and Union with multiple ovals...
- Draw 2 ovals.
- Subtract the top one from the bottom one.
- Draw a small oval near the top of the half moon, make sure it overlaps the edges of the half moon, duplicate this smaller oval (you will need the 2nd one later).
- Subtract one of the small ovals from the half moon.
- Select the half moon and hit Layers / Paths / Flatten (if a warning comes up, flatten it anyway), now double click the top pointy part of the half moon and delete it.
- And finally select the other small oval and Union it with the half moon.
You should be able to figure out the rest now...
Download the sketch file here (note, I just eyeballed the 2 small ovals at the edge of the half moon, so it's a bit "bubbly", if you take your time you will be able to align it sharp.