Custom Cut for Stair Tread

I need a custom-shaped cutout on the back of a 3-inch thick wooden stair tread to accommodate a metal plate. only need 5/16 inch deep . its white oak so probably do in increments of 1/8"

Requirements:
- Experience with woodworking and precision cutting
- Ability to create custom shapes as per specifications
- Tools for cutting thick wood safely and accurately

Please provide samples of similar work.