You can often fix this without disturbing the glass tile. It depends on which part sticks out: the toggle and the thickness of the cover plate normally project from the wall, but the plate’s back edge should sit against the tile.

Turn off the disposal circuit at the breaker and verify that power is off before removing the cover or adjusting the switch.

- If the switch sits too far forward, check for excess spacers or an incorrectly fitted box extender behind its metal mounting strap. Correcting either may let the cover sit against the backsplash. Don’t force the switch inward or overtighten screws against the glass.
- If the electrical box projects beyond the tile, an electrician needs to reposition it. Access through the wall behind it, if available, may avoid disturbing the backsplash.
- If tile or hardened adhesive blocks the switch, have the tile installer correct the opening. Chiseling installed glass mosaic can crack nearby pieces.

A box extender generally brings a recessed box forward, so adding one won’t fix a switch that already sticks out. Don’t push the assembly too far back, either: U.S. electrical rules generally limit box setback behind noncombustible tile to ¼ inch. [NFPA guidance, §314.20](https://docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2025_NEC_P08_FD_PrelimFR.pdf)

Since the backsplash is newly installed, ask the installer to return and coordinate with an electrician if the box needs moving. A photo of the gap around the cover would help identify the fix. A photo of the mounting beneath the cover would also help, with power verified off before removing it.