Preheat oven to 350°F. Spread the raw almonds and cashews in a single layer on a baking sheet. Roast for 18–20 minutes, turning the tray halfway through, until golden and fragrant. Watch closely near the end to prevent burning.
Remove the tray from the oven and let the nuts cool for 5–10 minutes—they should still be warm but not hot when blending.
Transfer the nuts to a high-powered blender or food processor. Blend on high speed, scraping down the sides as needed, until the mixture turns into a smooth, creamy nut butter. This may take several minutes depending on your machine.
Add the maple syrup, vanilla extract, cinnamon, ginger, cloves, nutmeg, and salt. Blend again until fully combined. If you'd like a runnier consistency, add the optional canola oil and blend until smooth.
Spoon the spread into a clean glass jar and refrigerate. It will keep for 2–3 weeks. Let it sit at room temperature for a few minutes before using, as it firms up when chilled.
