Wash, peel, and core apples. Slice into water containing ascorbic acid to prevent browning. Drain.
Place drained slices in a large pot. Add 1-2 cups of water. Stirring occasionally to prevent burning, heat quickly until tender (5 to 20 minutes, depending on maturity and variety).
Press through a sieve or food mill or skip the pressing step if you prefer chunk-style sauce.
Add sugar and cinnamon if desired. Reheat sauce to boiling.
Fill jars with hot sauce, leaving ½ inch of headspace.
Cap and seal. Place in canner with 2 to 3 inches of hot water.
Pressure cook for 10 minutes on High pressure. Once done, allow pressure to come down naturally before opening the cooker.