Preheat oven to 375°F. Line two baking sheets with parchment paper.

Whisk 1 cup flour, ¾ tsp kosher salt, and ½ tsp baking soda in a medium bowl.

Brown 4 Tbsp unsalted butter in a skillet over medium-high heat until dark golden and nutty, about 1–2 mins. Transfer to a large bowl and stir in ¼ tsp ground cinnamon.

Whisk ¾ cup brown sugar, ½ cup granulated sugar, and ½ cup neutral oil into the browned butter until smooth. Add 1 lightly beaten egg, 1 egg yolk, and 1 tsp vanilla extract; whisk until fully blended.

Stir in the flour mixture until just combined, then fold in 3 cups oats and ½ cup raisins.

Divide dough into 20 portions (about 3 Tbsp each), placing 10 on each baking sheet. Flatten each mound into a 2½-inch disk.

Bake one sheet at a time until edges are set and lightly browned but centers remain soft, 8–10 mins, rotating halfway.

Cool cookies on the sheet for 5 mins, then transfer to a wire rack to cool completely.