Place butter in a small sauce pan and cook over medium heat until the butter becomes bubbly, fragrant and nutty smelling - swirl and stir as needed.
Watch closely for small brown bits to begin forming on the bottom of the pan - this will happen around 5 minutes.
As soon as you begin to see brown bits in the butter, remove the butter from the heat. Transfer butter to your mixing bowl and allow to cool for a few minutes before proceeding with the recipe.
For the Apple Crisp
Preheat oven to 350° Combine the sliced apples in a large mixing bowl with the flour, brown sugar, vanilla, lemon juice, cinnamon and ginger. Mix until the apples are well coated with the flour, sugar and spices. Evenly arrange the apples in your favorite 8 inch baking pan.
In a medium mixing bowl, combine the oats, flour, sugar, brown sugar, cinnamon, mace and salt. Mix gently with a fork. Slowly pour in the cooled brown butter and use a fork to combine the dry ingredients with the butter. Sprinkle evenly over the apple filling.
Bake the apple crisp for 40-45 minutes at 350°. Once the apples are bubbly and the top is golden brown, remove the crisp from the oven. Allow the crisp to cool for 10-15 minutes before serving. Serve apple crisp in your favorite dessert bowls with a big scoop of your favorite vanilla ice cream! Enjoy!