Classic Farmhouse Kitchen Island with 4x4 Legs

Set a circular saw's blade depth to 1-1/2". Make repeated cuts every 1/4" across the notch area on each 4x4 leg, then clear the waste with a chisel.

Attach the bottom stretcher into the notched area with 2-1/2" screws and wood glue. Drill two 1-1/2" pocket holes on each end of the top end apron board and attach to the legs, checking for square. Drill pocket holes facing upward on the inside of the aprons for attaching the tabletop later. Build two leg sets.

Drill two 1-1/2" pocket holes on each end of the side apron boards. Attach to the legs with 2-1/2" pocket hole screws and glue, checking for square.

Attach the under-table supports to the side aprons with pocket holes, drilling upward-facing holes for the tabletop attachment.

Build the shelf from the 2x6 boards and attach to the bottom stretchers.

Build the tabletop as its own flat panel from the 2x6 boards, then attach to the aprons and supports.