01 - Bring a generous pot of salted water to a rolling boil. Cook the tagliatelle or fettuccine according to package directions to achieve an al dente texture. Drain the pasta, reserving 2 tablespoons of the cooking water for later use.
02 - Melt the butter in a skillet over medium heat. Introduce the crushed pretzels and brown sugar. Continue to stir and toast the mixture for approximately 3–4 minutes until it develops a golden hue and releases a fragrant aroma. Transfer to a plate to cool and crisp.
03 - In a medium saucepan, combine the granulated sugar and water. Cook over medium heat, gently swirling the pan (avoid stirring) until the mixture transforms into a deep amber color, typically taking 6–8 minutes. Remove the saucepan from the heat and carefully whisk in the heavy cream, butter, and sea salt. The mixture will foam vigorously. Continue whisking until smooth, then incorporate the vanilla extract.
04 - Add the drained pasta to the saucepan containing the salted caramel sauce. Toss gently to ensure the pasta is thoroughly coated. If a silkier sauce consistency is desired, add a small amount of the reserved pasta water.
05 - Portion the caramel-coated pasta evenly among serving bowls. Generously sprinkle the pretzel crunch over each serving. As an optional enhancement, garnish with flaky sea salt, additional crushed pretzels, or a dollop of whipped cream. Serve immediately to best enjoy the textural contrast.