The layout is that of a Greek cross, with an opening from the presbytery to a large chapel-like area, now the sanctuary of the Passion, where the nuns could attend services apart from the community.

The elaborate dome frescoes, however, were painted over a century after the church's construction, circa 1768, by Michele Antonio Milocco.

In the chapel to the left, dedicated to St Francis of Sales and Alessandro Trona, is an altar (1730) designed by Filippo Juvarra.

The altarpiece depicts St Francis providing the rules of the Order to the Saint Giovanna Francesca Fremiot di Chantal.

Frescoes for the nun's choir, depicting scenes from the Passion of Christ were painted by Paolo Emilio and Luigi Morgari.