Cook pasta according to package directions for al dente. Drain and keep warm.
Over medium-high heat, heat 2 tablespoon of olive oil in a large skillet.
Season chicken with salt and pepper. When hot, add the chicken and brown on all sides. Don't crowd the chicken - cook in batches, if necessary.
When chicken is just about done, add the garlic and let it cook for about 30 seconds - until you smell the aroma of it. Turn heat to low. Toss the spaghetti noodles in with the chicken and garlic.
While chicken is cooking, prepare the sauce. In a small bowl, combine all ingredients for the sauce and mix with a whisk until smooth. Taste and adjust as needed. Add more sriacha if you need too.
Pour about 2/3 of the sauce into the hot chicken and pasta, tossing to combine.
Warm the remaining sauce in the microwave and use to top each serving of chicken and pasta.