Grease a 15 x 10 x 1-inch baking pan (OR an 18 x 13 x 1-inch half sheet pan for thinner toffee) and heat-resistant spatula; set aside.
Combine sugar, water, corn syrup, salt and butter in a 3-quart microwave-safe bowl.
Microwave on HIGH (100%) 5 minutes; stir. Continue to microwave 18 to 22 minutes, stirring every 7 minutes, until mixture is a golden brown caramel color (300°F on a candy thermometer). Note: Cooking time may vary depending on microwave oven.
Carefully remove from microwave; stir in 3/4 cup almonds and vanilla. Quickly pour mixture onto prepared cookie sheet; spread evenly with spatula. Cool 5 minutes.
Sprinkle chocolate chips evenly over warm toffee; let stand 5 minutes or until chocolate is melted. Spread chocolate over brittle until smooth. Top with remaining 3/4 cup almonds.
Let cool until chocolate is set. (TIP: Place in refrigerator for a few minutes to harden chocolate before removing from pan.) Gently twist pan to release toffee from pan, then break into pieces. Store in an airtight container.