Special equipment: 3 1/2-inch metal rings
In a small saucepan, heat the milk until lukewarm. Combine the milk, flour, water, butter, honey, yeast, baking powder and salt in the bowl of a stand mixer. Using the dough hook attachment, mix on high speed until completely blended and a soft dough has formed, 2 minutes. Remove the bowl, cover with a clean cloth or plastic wrap and put in a warm spot until risen and bubbly, about 1 hour.
Lightly spray a cast-iron or nonstick skillet or griddle with nonstick spray and heat over medium heat, about 5 minutes. Spray the metal rings well with non-stick spray and place them in the pan or on the griddle. Fill each ring with a scant 1/4 cup of the batter.
Cook until the crumpets are set and the bottoms are lightly golden brown, 3 to 5 minutes.
Carefully remove the rings, flip the crumpets and cook until completely cooked through and the bottoms are lightly golden brown, 3 to 5 minutes longer. While they are cooking, wash and spray the rings with nonstick spray for the next batch.
Butter the tops with the Whipped Butter and spread with the Orange-Blueberry Marmalade. Or split the crumpets and toast (like you would an English muffin), and spread with the Whipped Butter and Orange-Blueberry Marmalade.
Combine the cream and salt in the bowl of a stand mixer. Using the whip attachment, whip on high speed until the cream is light and fluffy and turns to butter. Using a rubber spatula, scrape the butter into a bowl and chill for 15 minutes before serving.
Using a vegetable peeler, remove the zest of the oranges and lemons. Cut the zest pieces into thin slices, then finely chop or grind and set aside.
Peel the remaining white part of the peel from the fruit and discard. Chop the fruit pulp, reserving any juice and set aside.
Place the zest and 1 1/2 cups water in a medium saucepan over high heat and bring to a boil. Reduce the heat, cover and simmer for 20 minutes, stirring occasionally. Add the reserved fruit pulp and juice, cover and simmer on low heat for an additional 7 minutes. Add the blueberries and simmer for 3 more minutes.
Stir the sugar into the fruit in the saucepan. Bring the mixture to a full rolling boil and cook exactly 1 minute, stirring constantly. Stir in the pectin. Remove from the heat and skim off any foam with metal spoon.
Serve at room temperature.