01 -
Melt butter in a small light-colored saucepan over medium heat. Stir as it foams, then watch for golden-brown milk solids and a nutty aroma, about 4–6 minutes. Immediately scrape into a heatproof mixing bowl. Cool 15 minutes until warm but not hot.
02 -
Stir both sugars into the browned butter, then beat in the egg and vanilla. In another bowl combine flour, oats, baking soda, cinnamon and salt.
03 -
Fold dry ingredients into the butter mixture. Pat the apple pieces dry and fold them in. Chill the dough 20 minutes while the oven heats to 180°C / 350°F.
04 -
Line two baking sheets. Divide the dough into 16 equal mounds, spacing them at least 5 cm apart, and flatten each slightly to about 1.5 cm thick.
05 -
Bake one tray at a time for 12–14 minutes, until the edges are golden and the centers look set but still soft. The second tray may need a minute less if it has warmed at room temperature.
06 -
Cool on the baking sheet for five minutes before moving to a rack for at least five minutes more. The apple keeps the middle soft; these are not crisp storage cookies.
07 -
Keep fully cooled cookies covered in the refrigerator for up to four days, allowing a portion to come to room temperature before eating. Freeze extra cookies individually.