Step 1Heat the oven to 300 degrees. Combine the almonds and oil in medium bowl and toss with a rubber spatula until coated. Crush the rosemary with mortar and pestle (or crumble with fingertips) and add it to the almonds with the cayenne and one-half teaspoon salt. Mix well.
Step 2Spread the nuts on a rimmed baking sheet. Bake 30 to 35 minutes, tossing or stirring every 10 minutes, until light brown and crisp to the core.
Step 3Immediately pour the nuts into a brown paper bag and add one-half teaspoon or more salt. Toss to coat well. Seal bag tightly and let stand at least 1 hour and preferably 2 hours before serving.