Especially for Monica!
Most of us learned to do the traditional granny square when starting off:
The Babette blanket also uses a solid granny square, a square I use a lot for baby blankets, for example, because little baby fingers won't get caught in the gaps between the stitches.
American English: DC = double crochet
[British English: TR = treble crochet]
This pattern is in American English terms, the British terms are in [brackets].
Start by chaining 4, then join with a slip stitch.
Chain 3 (counts as the first DC [TR]), do 2 DC [TR] into the ring. Chain 2, 3 DC [TR], chain 2, 3 DC [TR], chain 2, 3 DC [TR], chain 2 and join to the third chain of your first 'fake' DC [TR] - like this:
Either continue crocheting in the same colour or join a new one.
Chain 3 in a corner gap, then do 1 DC [TR] in each DC [TR] in the previous round, 1 DC [TR] in corner, chain 2, 1 DC [TR] in same corner gap, then continue with 1 DC [TR] in each DC [TR] of the round below, and 1 DC [TR] + chain 2 + 1 DC [TR] in each corner.
Second round done:
When I join the third colour, or continue with the same colour, I like to start in the corners. There are two reasons for this, both practical: (a) the starting chain-3/'fake' DC [TR] is less noticeable in the corner gap, and (b) when you finish your last row, you can leave a long yarn tail, which I later use to whipstitch the squares together.
The pointer shows where the starting chain-3/'fake' DC [TR] has been done in the corner:
After that, you just continue, round by round, till your square is the desired size.