You can bond directly to glass using Type 1 Bonded, although care should be taken to ensure the adhesive used is suitable for whatever finish or surface is present on the rear face of the glass.

Another option, especially if using thin glass or mirror, is to bond the glass to 3mm hardboard first, then use Type 1 Bonded fixes. This gives a reasonable 10mm standoff from the wall.

Alternatively, use thicker MDF or plywood backing panels with the Type 1 Fixes (or Type 1 Bonded) installed in the usual way, either face-fixed or rebated.