Preheat the oven to 350 degrees.
Grease a 9x13-inch baking pan with cooking spray and line it with parchment paper.
In a large bowl, cream your ¾ cup butter with the 3/4 cup granulated sugar and 3/4 cup light brown sugar. Mix with a hand mixer (or in the bowl of a stand mixer) until the butter is light in color.
Add in the eggs, 1 tsp vanilla extract, and 1/2 tsp almond extract. Mix until combined.
In a different large bowl, combine the 2 cups white flour, 1/2 teaspoon baking soda, and 1/2 teaspoon salt. Stir.
Add the wet ingredients to the dry ingredients and stir until just combined.
Add in the 1 cup of white chocolate chips and stir with a wooden spoon until just combined.
Press the cookie dough into your prepared 9x13-inch pan using your (freshly washed!) fingers.
Bake the bars for about 20-25 minutes or until the top is no longer shiny and the edges are starting to brown.
Remove from the oven and immediately top with the mini marshmallows.
Return to the oven for 1 minute and 30 seconds.
Gently press the marshmallows down with your wooden spoon or a spatula.
Spread the last ¼ cup white chocolate chips evenly over the cookie bars.
Spread the ¾ cup m&m's evenly over the bars.
Scatter the sprinkles over the whole thing.
Let your cookie bars cool completely before serving. Give them at least a couple of hours!