Pre-heat oven to 350°F. Lightly grease an 8x8 baking pan and line the bottom with parchment paper to ensure the cake will easily release from the pan.
Gently mix the strawberries with the cornstarch and sugar. Evenly layer the berries on the the parchment paper in the baking pan.
Sift together flour, baking powder, and salt. Set aside.
In a mixing bowl, whisk together eggs and sugar. The mixture should be slightly foamy.
Next, slowly add the oil and melted butter. Whisk the mixture as these ingredients are added. Follow the butter and oil with the milk and vanilla, continuing to whisk the batter.
Finally, slowly fold the flour mixture into the wet ingredients. Pour the finished batter over the strawberries.
Place cake in the oven for 45 minutes. Use a toothpick to check the center. The toothpick should come out clean.
Remove cake from the oven and cool for 15 minutes. To remove from baking dish, invert the pan over a plate and remove the cake.
Serve warm, room temp, or chilled.