Eclairs

Bahan-bahan (20 porsi)

• 100 g / 7 tbsp unsalted butter (, cut into 1 cm / 1/2" cubes)
• 1 cup water
• 1 cup plain/all-purpose flour
• Pinch cooking/kosher salt
• 4 large eggs (55-60g/2oz each) (, at room temperature (Note 1))
• 100 g / 3.5 oz 70% cocoa dark chocolate block (, finely chopped (Note 2))
• 2/3 cup thickened/heavy cream ((Note 3))
• 3 1/2 teaspoons corn syrup or liquid glucose ((Note 4))
• 3 cups thickened/heavy cream or whipping cream ((min 35% fat, Note 3))
• 1 cup mascarpone ((40%+ fat, Note 6))
• 1 2/3 cups icing sugar/powdered sugar (, sifted)
• 2 tsp vanilla bean paste or extract or, 2 vanilla pods ((Note 7))