Use a measuring tape to get the distance between the front and back of the counter inside the top edge.
Cut 2-inch-wide wood strips to the measurement in step 1. Use a power saw.
Slide the wood supports into the top of the cabinet so that they go from front to back. Insert screws at an angle through the supports and into the cabinets.
Get the length of the cabinet and measure out 2-inch by 6-inch wood planks to match the length. Cut along the measured mark with a power saw.
Place the planks on the cabinet and check the front overhang. If the planks hang over more than 1 inch, mark the difference and cut it off. Use a table saw to rip one of the boards.
Apply construction adhesive to the support strips and the top edges of the cabinet.
Wait a few minutes, and then lay the planks over the cabinet. If your cabinet is up against a wall, press the planks up to the wall. If not, allow the lip to hang over equally on both sides.
Drill 3-inch screws through the wood supports from underneath and up into the planks to secure the boards.