Preheat oven to 350°F (175°C).

In a large bowl, mix together the flour, salt, and cinnamon.

Add the brown sugar and salad oil to the flour mixture.

Using an electric mixer on medium speed, mix until the mixture is crumbly.

Remove 3/4 cup of the crumbly mixture and set aside for the topping.

To the remaining mixture in the bowl, add the baking soda, baking powder, egg, and buttermilk.

Mix until the batter is smooth.

Grease a 9 x 13 x 2-inch baking pan with butter.

Pour the batter into the prepared pan.

Sprinkle the reserved crumb topping evenly over the top of the batter.

Bake in the preheated oven for 25 minutes, or until a toothpick inserted into the center comes out clean.

Let cool slightly before cutting into squares.

Serve warm or at room temperature.