Whisk the all-purpose flour and baking soda together in a medium bowl until evenly blended. The dry mixture will look uniform and completely free of compact lumps.

Beat the room-temperature butter with the granulated sugar and packed light brown sugar on medium speed. The mixture will turn pale and fluffy after two to three minutes of creaming.

Reduce mixer speed to low and incorporate the salt, vanilla extract, and whole egg for about one minute. The wet base will become silky, glossy, and fully emulsified.

Add the whisked dry flour mixture into the wet ingredients and mix on low speed. Stop mixing as soon as the flour streaks are nearly absorbed to avoid overworking the gluten.

Fold the rolled oats and semisweet chocolate chips into the dough with a sturdy spatula, then cover and chill the bowl. The dough will turn thick, slightly tacky, and firm to the touch after resting in the refrigerator.

Heat your oven to 375 degrees F and line two large baking sheets with parchment paper. The preheated oven will ensure an immediate rise and quick edge caramelization.

Drop heaping two-tablespoon portions of chilled dough onto the prepared baking sheets, spacing each mound about two inches apart. The portions will sit high and round on the paper without slumping.

Bake the cookies for 8 to 10 minutes until the rims turn golden brown while the tops remain soft. A pale, dime-sized center signals that the cookies are ready to leave the heat.

Set the hot baking sheet on a counter for one to two minutes before moving the cookies onto a wire cooling rack. The warm centers will finish firming up while the base cools into a crisp bottom crust.