Combine sugar, corn syrup and salt in a 2-quart glass bowl. Microwave uncovered on high 5 minutes. Stir in pecans. Microwave 1½ minutes. Stir in vanilla and butter. Microwave one minute and 45 seconds or until candy is color of peanut butter. Stir in baking soda (mixture will bubble).
Quickly pour candy onto a lightly greased rimless baking sheet. (Pour as thinly as possible without spreading candy.) Cover brittle quickly with parchment paper and use a rolling pin to thin out candy; peel off parchment. Sprinkle granola over brittle. Cool brittle completely; break into pieces.
Place chocolate squares and shortening in a small microwave-safe bowl. Microwave uncovered on high 1½ to 2 minutes, stirring after one minute. Dip each piece of brittle halfway into chocolate mixture. Place dipped brittle on parchment paper to harden. Store in an airtight container.