Trim and peel 8 asparagus tips and set aside. Slice remaining asparagus into thin rounds, discarding the woody ends. Heat a saucepan over medium-high heat, add butter, shallots and garlic and sauté, stirring occasionally, until tender but not coloured (2-3 minutes). Add sliced asparagus and stir occasionally until asparagus starts to soften (2 minutes), then add stock, season to taste and simmer until asparagus is tender (4-5 minutes). Remove from heat and strain, reserving cooking liquor, then blend asparagus in a blender until smooth, adding a small amount of cooking liquor if needed to form a smooth purée. Pass purée through a fine sieve and refrigerate until chilled (you’ll need 220ml).
Preheat a steam oven to 90C. Whisk eggs, yolks and cream and reserved 220ml asparagus purée in a bowl to combine and season to taste. Pass through a fine sieve. Pour 125ml into four 185ml heatproof bowls and cover with plastic wrap. Steam in a steam oven (or steam very gently in a steamer basket placed over a saucepan of simmering water) and steam until just set (25-30 minutes). Remove and cool to room temperature. If not serving immediately, refrigerate until required; custards will keep covered with plastic wrap for 2 days.
Blanch asparagus tips in boiling water (1-2 minutes), then refresh in iced water. Set aside to drain.
For speck dressing, heat a saucepan over medium heat, add 1 tbsp extra-virgin olive oil, then shallots and chilli, and stir occasionally until tender but not coloured (1-2 minutes). Add speck, and stir until light golden-brown (5-6 minutes), then add chicken stock and sherry vinegar and reduce by half (3-4 minutes). Add remaining olive oil and season to taste with freshly ground black pepper.
To serve, bring asparagus custards to room temperature if chilled, then spoon speck dressing on top, garnish each with 2 asparagus tips and finish with a few grinds of freshly cracked pepper to taste.