Preheat the oven to 350°F (175°C).
In a medium-sized bowl, add the oats and pour the boiling water over them. Stir to combine and set aside.
In a mixing bowl, combine the butter, brown sugar, and granulated sugar. Mix well.
Add the eggs to the sugar mixture and mix until combined.
Pour the soaked oats (along with the liquid) into the mixer bowl. Stir with a wooden spoon.
Add the flour, baking powder, salt, cinnamon, and nutmeg to the mixture. Stir until completely combined.
Butter a 9x13 inch baking pan or spray it with non-stick cooking spray.
Pour the batter into the prepared pan and smooth it evenly.
Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean.
Remove the cake from the oven.
To make the icing, combine the butter, brown sugar, granulated sugar, cream, coconut, and pecans in a saucepan. Cook over medium heat, stirring often, until the mixture starts to bubble. Cook for an additional 5 minutes.
Remove the icing from the heat and spread it evenly over the warm cake.
Place the cake under the broiler for 3-5 minutes until the icing is golden brown and toasted.
Cool the cake on a wire rack.
Slice and serve warm or at room temperature.