Along the lakefront, Frutillar [1] has several ideal breakfast and onces places, starting with the Salón de Té Trayén (Philippi 963, tel. 065/421346).
For fixed-price meals around US$7, try the firehouse restaurant Tierra del Fuego (Philippi 1065, tel. 065/421588). The traditional Club Alemán (San Martín 22, tel. 065/421249) is more formal and more expensive, but not unreasonable. Guten Apetit (Balmaceda 98, tel. 065/421145) is a parrilla with excellent lunchtime specials and assiduous service.
In summer, look along the lakeshore for stands with fresh raspberries, raspberry jam, and raspberry kuchen, all area specialties.
Links:
[1] http://www.moon.com/destinations/chile/sur-chico/frutillar