First, unplug the toaster and strip the heating element. Replace it with a small, low‑power microcontroller board—something like a Nordic nRF52840 that can run on a few milliamps when idle. Wire the MCU to the toaster’s existing contacts and drive the heating element through a logic‑level MOSFET. The MCU can monitor the element’s temperature, log usage, and push data over BLE or Wi‑Fi when you’re ready. For resilience, add a watchdog timer, two redundant firmware paths, and a tiny capacitive battery backup so the unit can recover from power glitches. Keep the code clean: modular, well‑commented, no hidden tricks—code purity beats clever hacks. And test by cycling the MOSFET on and off to make sure the safety circuits kick in. That’s the sweet spot: no wasteful parts, just a lean, smart toaster that learns how it’s used.

Sounds like a plan. Keep the element’s resistance in mind, and put a small 0.1µF capacitor across the MOSFET drain to shave off any ringing from the spark. For logging, just sample the thermistor every second when the toast is on, round to the nearest 0.5°C, and drop that into a small circular buffer. When you flash the firmware, check that the watchdog resets if the MCU stalls—no endless loops. Let me know the average spike and the max idle current, and we can shave a few µA from the BLE beacon. Keep it lean, keep it tight, and the toaster will stay smart without turning into a light show.