Heat oven to 350°F. Line an 8x8-inch baking pan with parchment paper.
In a large bowl, add the olive oil, cane sugar, dark brown sugar, vanilla extract, and milk. Mix on low speed with a hand mixer to combine completely.
Add in the flour, baking powder, and sea salt and mix to combine. Scrape batter on sides of bowl to ensure it's all evenly mixed.
Transfer the batter to the prepared baking pan and spread evenly.
In a small bowl, add the strawberry jam and cornstarch and mix together.
Drop spoonfuls of jam on top of the batter and using a butter knife, swirl it into the batter.
Bake for 30 minutes or until a toothpick inserted in the center comes out clean.
Sprinkle with flaky sea salt immediately after coming out of the oven. Allow to cool completely in the baking pan.
Cut into 9 bars. Store in an airtight container in the fridge for up to 5 days.