1. Preheat oven to 350 degrees.
2. Whisk together flour, sugar and baking powder in a large mixing bowl.
3. Add butter, egg whites, vanilla, sour cream, milk and creamer and mix on medium speed just until smooth. Do not over mix.
4. Fill cupcake liners a little more than half way.
5. Bake 18-20 minutes.
6. Allow to cool for 1-2 minutes, then remove to cooling rack to finish cooling.
1. While cupcakes cool, make macadamia brittle. Line a cookie sheet with a silicon baking mat, set aside.
2. Stir together sugar, water and salt in a medium saucepan.
3. Cook over high heat without stirring, until sugar begins to melt and turn golden, about 3 minutes.
4. Continue to cook, stirring occasionally, until sugar has melted and mixture turns golden amber, about 10 minutes. Mixture will turn amber quickly, so keep a close eye on it.
5. Once mixture turns amber, stir in macadamia nuts.
6. Immediately remove mixture from heat and pour onto baking mat. Quickly spread to about 1/2 inch thick.
7. Let cool completely, about 15 minutes. Break brittle into pieces.
1. Place 1/2 cup of butter and brown sugar into a microwave-safe bowl. Microwave for about 30 seconds at a time, stirring after each interval, until the sugar is mostly dissolved, about 3 minutes. It’ll boil and bubble up. Set caramel aside to cool.
2. Cream remaining 1/2 cup butter and shortening until smooth.
3. Add 3 cups powdered sugar and 1 tbsp creamer and beat until smooth.
4. Pour caramel into icing and mix until smooth.
5. Add another 1-2 cups of powdered sugar.
6. Add more creamer to reach desired icing consistency.
7. Ice cooled cupcakes, then top with a piece of macadamia brittle.