Spread nuts, pretzels and popcorn onto a Silpat mat.
In heavy based saucepan, place sugar cream, butter, salt and rum if using. Cook on a low heat stirring occasionally (Induction level 6) until sugar has melted without any grainy residue. Increase heat to around Induction 8 and bring to approximately 132°C (Please use a candy thermometer if you have one for an accurate result.) If you don't have one, use the hard ball test.
Add vanilla bean paste and quickly stir into caramel, pour over popcorn and nut mix, spreading quickly to cover as much of the popcorn etc as possible. Place chocolate buttons directly onto the hot toffee and allow to melt before spreading with a palate knife or spatula to form a topping.
Allow to set completely before breaking into pieces and storing in the fridge.