Set pressure cooker to "sear", adjust time to 10 minutes, and press start/stop. Add milk and cream. Bring to a boil. Constantly watch milk to prevent scorching.
Once milk and cream are boiling, turn off pressure cooker and immediately add salt and lemon juice. Stir.
Close lid but do not lock. Let sit for 15 minutes. After 15 minutes, curds should have separated from whey.
Strain through cheese cloth for 15-20 minutes. Ricotta is ready to serve.