Adjust oven rack to upper-middle position and heat oven to 325ºF degrees.

Make parchment paper sling for a 13 by 9-inch baking pan by folding 2 long sheets of parchment; first sheet should be 13 inches wide and second sheet should be 9 inches wide. Lay sheets of parchment in pan perpendicular to each other, with extra parchment hanging over edges of pan. Push parchment into corners and up sides of pan, smoothing parchment flush to pan. It sometimes helps to use a little nonstick spray to help the parchment paper stick to the pan.

Whisk maple syrup, sugar, vanilla, and salt together in large bowl, then slowly whisk in oil. Fold in oats and almonds until thoroughly coated.

Transfer oat mixture to prepared pan and spread across bottom into thin, even layer. Using the back of a measuring cup, compress oat mixture until very compact. Bake until lightly browned, 30 to 35 minutes, rotating pan halfway through baking.

Remove granola from oven and let cool on a wire rack to room temperature, about 1-2 hours. The longer you let it cool, the better success you’ll have in getting large chunks that don’t crumble apart. Using parchment overhang, lift granola out of pan. Break cooled granola into pieces of desired size and transfer to large clean bowl. Add raisins and gently toss to combine. Granola can be stored in airtight container for up to 2 weeks.