1. Prepare the vanilla cream filling:
- In a saucepan, combine the heavy cream, granulated sugar, and butter. Cook over medium heat, stirring until the butter melts and the sugar dissolves.
- Remove from heat and stir in the vanilla extract. Gradually whisk in the powdered sugar until smooth and creamy. Set aside to cool completely.
2. Make the caramel shell:
- In a large heavy-bottomed saucepan, combine the butter, granulated sugar, brown sugar, corn syrup, heavy cream, and salt. Heat over medium heat, stirring occasionally, until the mixture reaches 245°F (118°C) on a candy thermometer (firm-ball stage).
- Remove from heat and stir in the vanilla extract.
3. Assemble the filled caramels:
- Pour half of the caramel mixture into a parchment-lined 9×13-inch pan. Let it cool slightly until it firms up but is still pliable (about 10 minutes).
- Spread the vanilla cream filling evenly over the first layer of caramel.
- Pour the remaining caramel over the cream layer, spreading gently to cover completely.
4. Cool and cut:
- Let the caramel cool at room temperature for 4–6 hours or refrigerate for 2 hours until fully set.
- Once set, use a sharp knife to cut the caramel into squares or rectangles.
5. Wrap and store:
- Wrap each caramel in wax paper or candy wrappers to prevent sticking. Store in an airtight container at room temperature for up to 2 weeks.