Preheat oven to 350°F.
Butter a 13”x9” rectangle pan. Pour 1 ⅓ cups boiling water over quick oats and stir until well combined. Set aside to cool.
In a small bowl, sift together flour, cinnamon, baking soda, and salt. In a stand mixer or large mixing bowl, cream butter with brown and white sugars. Once blended well, add eggs, and beat an additional minute on medium speed. Add the dry ingredients to the mixer bowl, and blend for 1 minute. Add the oatmeal mixture 2 tablespoons at a time, and blend an additional minute.
Pour in the prepared pan and bake for 35 minutes.
When 10 minutes remain on the cake, start making the topping. Place a saucepan over medium heat and add brown sugar, butter and milk. Cook until brown sugar is dissolved and mixture comes to a boil, then turn off the heat and stir in vanilla, coconut and pecans. Once the cake has finished baking, pour the topping over the cake and spread evenly. Place the cake under the broiler for 1-3 minutes or until the topping is golden brown.