School of simple drawings

Step one:

First draw a wavy line.

Step 2:

Then draw an inverted trapezoid below and a rectangle below.

The third step:

On top, draw another half oval.

Step 4:

On the inside, draw a flat oval shape as the concave part for the filling.

Step 5:

You can also add some short arcs on the edges as a little structure.

Step 6:

Finally, apply a nice color, and the pie is ready.