Preheat oven to 350 degrees.
Melt 1 tbsp. butter in small microwavable bowl. Toss pecans in butter. Spread onto baking sheet and lightly salt. Place in oven to bake for 10-12 minutes, stirring once or twice. Remove from oven and let cool completely.
In a medium mixing bowl, whisk egg yolks and set aside.
In a separate mixing bowl, pour 1 cup of heavy cream in, then place a mesh sieve over top.
In a medium sauce pan set over medium-low heat, melt butter. Whisk in brown sugar and salt (the mixture will become clumpy). Stir in 1 cup of heavy cream and the whole milk. Once the mixture is warm, add to bowl with yolks. Stir continuously to temper the eggs.
Return mixture to medium heat. Add butterscotch chips, stirring constantly, until the mixture thickens and it reaches approximately 160-170 degrees. Immediately remove and pour through sieve into remaining cream. Add vanilla and stir.
Cover the bowl and transfer to the refrigerator until completely cooled or place/stir over an ice bath to chill.
Once the mixture is chilled, freeze in an ice cream maker according to manufacture's directions. After 15 minutes, add toasted pecans. Transfer into an freezer-safe, air-tight container. Freeze for 2-4 hours.