Line an 8×8-inch pan with aluminum foil, spray with cooking spray; set aside.
In a large microwave-safe bowl, combine oil, corn syrup, sugars, and cook on high power for 90 seconds. Stop and stir the mixture.
Return bowl to microwave and cook for 90 more seconds. Stop and stir the mixture.
Stir in shredded coconut, oats, cinnamon, vanilla, and optional salt. Note – when adding the shredded coconut and oats, add them slowly, bit by bit, rather than all at once. I found the measurements worked perfectly, but because coconut oil, coconut, and oats vary, add dry ingredients until mixture combines, noting it will be quite wet. It solidifies and firms up as it cools.
Turn mixture out into prepared pan, packing it down with a spatula.
Optionally, melt the chocolate in a small, microwave-safe bowl, about 1 minute on high power, or until chocolate can be stirred smooth.
Even drizzle chocolate over bars. I followed the swirling pattern outlined here.
Cover pan with foil to prevent frigde smells, and refrigerate until set and firm, about 2 hours. Slice bars into desired shapes. Especially in warmer months, I prefer to store the bars in the fridge rather than at room temperature so the coconut oil stays solid and bars are firmer. They will keep for up to up to 1 month in the fridge, or up to 6 months in the freezer.