Choux Pastry:
• Water | --- | 1 cup
• Butter | --- | ½ cup
• All-Purpose Flour | --- | 1 cup
• Salt | --- | ¼ teaspoon
• Large Eggs | --- | 4

Filling:
• Cold Milk | --- | 2 ½ cups
• Instant Vanilla Pudding Mix | --- | 1 (5 ounce) package
• Heavy Cream | --- | 1 cup
• Confectioners' Sugar | --- | ¼ cup
• Vanilla Extract | --- | 1 teaspoon

Icing:
• Semisweet Chocolate | --- | 2 (1 ounce) squares
• Butter | --- | 2 tablespoons
• Confectioners' Sugar | --- | 1 cup
• Vanilla Extract | --- | 1 teaspoon
• Hot Water | --- | 3 tablespoons

1. Preheat the oven to 450 degrees F (230 degrees C). Grease a cookie sheet; set aside.
2. Make choux pastry: Combine water and butter in a medium pot. Bring to a boil, stirring until butter melts completely. Reduce heat to low; add flour and salt. Stir vigorously until mixture leaves the sides of the pan and begins to form a stiff ball. Remove from heat.
3. Add eggs, one at a time, beating well after each addition until incorporated. Using a spoon or pastry bag fitted with a No. 10 or larger tip, spoon or pipe dough onto the prepared cookie sheet in 1 1/2x4-inch strips.
4. Bake in the preheated oven for 15 minutes. Reduce heat to 325 degrees F (165 degrees C) and continue baking until the bottoms sound hollow when lightly tapped, about 20 more minutes. Cool completely on a wire rack.
5. Make filling: Combine milk and pudding mix in a medium bowl according to package directions. Beat heavy cream with an electric mixer in a separate medium bowl until soft peaks form. Beat in confectioners' sugar and vanilla. Fold whipped cream into pudding.
6. Cut tops off of cooled pastry shells with a sharp knife. Fill shells with pudding mixture and replace tops.
7. Make icing: Melt chocolate and butter in a medium saucepan over low heat. Stir in confectioners' sugar and vanilla. Stir in hot water, 1 tablespoon at a time, until icing is smooth and has reached desired consistency. Remove from heat and cool slightly.
8. Drizzle chocolate icing over filled eclairs. Store in the refrigerator until serving.