Place the melted butter in a large bowl, then add the granulated and light brown sugars; mix until smooth and combined.
Stir in the egg, vanilla extract, and almond extract until evenly incorporated.
Add the baking soda and salt, then gradually mix in the all-purpose flour until the dough is smooth and comes together; do not overmix.
Fold in the sliced almonds and Almond M&Ms until evenly distributed through the dough.
Line a baking sheet with a silicone mat or parchment paper. Use a tablespoon or 2-tablespoon scoop to portion dough into balls; place them on the sheet, cover with plastic wrap, and chill for at least 1 hour.
Preheat the oven to 350°F (175°C) and line a second baking sheet with parchment or a silicone mat.
Arrange the chilled dough balls about 2 inches apart on the prepared baking sheet and top with additional Almond M&Ms if desired.
Bake the 2-tablespoon cookies for 11–15 minutes, until the edges are light golden and the tops are no longer glossy.
Let the cookies cool on the baking sheet for at least 10 minutes before transferring to a wire rack to cool completely.