Sea Freeze Ice Cream Shop Brownies

Source: Sea Freeze Ice Cream Shop, Hyannis (this shop has been closed for a very long while)

2/3 cup vegetable oil
4 large eggs
1/2 cup cocoa powder
2 cups granulated sugar
1 1/2 cups all-purpose flour
1 teaspoon baking powder
1 teaspoon vanilla extract
1 teaspoon salt

Mix oil, eggs, cocoa, sugar and blend well. Sift dry ingredients in and beat well with wooden spoon till all flour is off the bottom of the bowl. Add the vanilla extract and mix thoroughly. Pour into an oiled 13 x 9-inch pan and spread evenly to the corners. Bake at 375 degrees F for 20 to 30 minutes.