In a microwave, melt baking chips with cream until smooth, stirring every 30 seconds. Stir in vanilla paste and extract. Set aside to cool slightly. Meanwhile, in a heatproof bowl of a stand mixer, whisk egg whites, sugar, cream of tartar and salt until blended. Place over simmering water in a large saucepan over medium heat. Whisking constantly, heat mixture until a thermometer reads 160°, 8-10 minutes.
Remove from heat. With whisk attachment of stand mixer, beat on high speed until cooled to 90°, about 7 minutes. Gradually beat in butter, a few tablespoons at a time, on medium speed until smooth. Beat in cooled baking chip mixture until blended.
