Heat water, butter, sugar, vanilla and salt in a medium-size saucepan until simmering and butter has melted. Remove from heat and dump in flour all at once. Mix vigorously with a spoon until the mixture forms a smooth ball and no floury bits are visible. Let cool 5 to 10 minutes, then add eggs, one at a time. You can beat them in with a large whisk and strong arm, or use a hand- or stand mixer. Be warned that the dough really likes to ride up the beaters of a hand mixer, so keep it pushed down. Transfer churros to a pastry bag or strong gallon Ziploc bag with a corner snipped off, fitted with a large closed star tip. Heat oven to 200 degrees to keep churros warm while you fry them in batches. Line a large plate with a couple layers of paper towels. Add oil to Dutch oven or cast iron skillet until it measures about 1 1/2 inches deep and heat over medium/medium-high heat to 375 degrees. Gently drop a few churros at a time into the oil and fry until deep golden brown on all sides, which will take about 6 minutes. Turn them frequently so that they cook evenly. Adjust heat as needed so that the oil does not dip below 350 degrees. Once churros are cooked, remove from oil and drain on towels for a minute before transferring to a tray in the oven to keep warm. Return your oil to 375 degrees before adding more churros. Once all churros are fried, combine cinnamon and sugar on a plate. Roll warm churros, one by one, in sugar to coat, spooning more cinnamon-sugar on as you do for best coverage. Tap off excess. Do not let warm churros sit in cinnamon sugar for longer than needed to coat or the sugar will get clumpy. Heat cream, chocolate and salt in a bowl in microwave in 30 second bursts, whisking between them, until chocolate has melted.