Lay out the almonds on a baking sheet in a single layer. Roast the almonds in the oven until they are just starting to darken and you can smell them, approximately 10-15 minutes. Do NOT overcook. If anything, err on the side of under toasted so they do not burn. Let them cool slightly for 10 minutes.
While the almonds are still warm, place the almonds in a food processor. Blend until in forms a paste, then turns into the consistency of almond butter. You will need to stop the processor and scrape down the sides every few minutes.
Once you get the consistency you want, add the cinnamon and salt. Process just to combine, a couple seconds. Taste and add more cinnamon or salt as desired.
Notes
It might look like the almond butter will never form for a while, but keep processing. It takes time for the oil to be released from the almonds. It is important to process the almonds when they are still warm because it will help the oils release and make the butter.