Here is the block set out and ready to go.
Here I've added the first border and trimmed it down to size.
And the second border.
The third border added.
And finally the last border to make up the finished block.
Here is the block set out for the approach without adding the extra seam allowance. The centre squares have been prepped for square-in-a-square.
Here the centre square is done. Next up is the triangles method for square-in-a-square.
And here is the centre completed.
Now the next border has been added.
And the final border added to make up our next block.