Before anything else, set your oven to 350°F (175°C). Line your baking sheet with parchment paper. This step ensures even baking and avoids sticky cleanup.
In a large bowl, cream the softened butter with the granulated and brown sugars. Beat until the mixture becomes fluffy and pale. This step builds the cookie’s chewy base and balances sweetness.
Crack in the egg and pour in the vanilla extract. Mix until the batter is smooth and silky. You’ll notice it getting thicker and more golden in color.
In a separate bowl, whisk together the flour, baking soda, and salt. Slowly add this dry mix to the wet batter. Stir gently until everything just comes together — don’t overmix!
Time to add the fun stuff! Gently fold in the semi-sweet chocolate chips and Rice Krispies. Stir just enough so every scoop of dough has a little bit of both.
Scoop out rounded tablespoons of dough and place them on the prepared sheet, spacing about 2 inches apart. Pop them in the oven for 10 to 12 minutes, or until the edges are golden.
Let the cookies cool on the tray for 5 minutes before transferring them to a cooling rack. This step lets them firm up while staying chewy in the center.