Beat 1 cup butter and brown sugar in a large bowl until smooth and creamy. Stir in eggs, 2 teaspoons vanilla extract, and 1/2 teaspoon almond extract; mix well. Combine oats, flour, sliced almonds, baking soda, and 1 teaspoon salt in another bowl; stir into butter mixture until batter is just mixed. Spread 2/3 batter into a 10x15-inch rimmed baking sheet.
Heat chocolate chips, condensed milk, 2 tablespoons butter, and 1/2 teaspoon salt in a saucepan over medium heat until chocolate is melted, about 5 minutes, stirring occasionally. Remove from heat and stir in remaining 2 teaspoons vanilla extract and 1/2 teaspoon almond extract. Spread chocolate mixture into baking sheet over oat batter. Spoon remaining 1/3 oat batter over chocolate.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, 20 to 25 minutes.