Caramel Corn Popcorn Balls

Lightly coat a large nonreactive bowl with nonstick spray. Add popcorn and almonds and toss to combine.

Combine sugar, butter, and ¼ cup water in a medium saucepan. Bring to a boil, stirring to completely dissolve sugar. Once sugar is dissolved and mixture is clear, cook, without stirring, until mixture begins to caramelize in spots, about 3 minutes. Continue to cook, stirring occasionally with a heatproof spatula to ensure even caramelization, until caramel is light amber, about 4 minutes.

Using heatproof spatula, stir in marshmallows, rosemary, salt, and cayenne, if using. Cook, stirring occasionally, until caramel is smooth, about 1 minute.

Remove from heat and stir in baking soda (mixture will bubble). Immediately pour over popcorn mixture and toss with 2 heatproof spatulas (the caramel will become very stretchy, with lots of thin webs of sticky stuff). Spray hands with nonstick spray and form popcorn mixture into 2" balls (you should have about 14 balls). Transfer to a rimmed baking sheet and let sit at least 30 minutes before serving.

Do Ahead: Popcorn balls can be made 5 days ahead. Cover and store at room temperature.