Creamy Orecchiette With Spring Onions, Fennel, and Bacon

Ingredients

• slices thick-cut bacon
• pound spring onions, trimmed, white and green parts divided and thinly sliced
• fennel bulb , cored and thinly sliced, fronds reserved
• water
• Kosher salt
• teaspoon baking soda
• heavy cream
• pound dried orecchiette pasta
• Freshly ground black pepper
• grated Parmigiano-Reggiano, plus extra for serving